diff --git a/src/libslic3r/GCode/ToolOrdering.cpp b/src/libslic3r/GCode/ToolOrdering.cpp
index 52ea76a619..1f60f56f10 100644
--- a/src/libslic3r/GCode/ToolOrdering.cpp
+++ b/src/libslic3r/GCode/ToolOrdering.cpp
@@ -1102,57 +1102,37 @@ void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first
     std::vector<std::set<int>>geometric_unprintables = get_geometrical_unprintables(m_print->get_unprintable_filament_ids(), print_config);
     std::vector<std::set<int>>physical_unprintables = get_physical_unprintables(used_filaments, print_config);
 
-    if (nozzle_nums > 1) {
-        filament_maps = m_print->get_filament_maps();
-        map_mode = m_print->get_filament_map_mode();
-        // only check and map in sequence mode, in by object mode, we check the map in print.cpp
-        if (print_config->print_sequence != PrintSequence::ByObject || m_print->objects().size() == 1) {
-            if (map_mode == FilamentMapMode::fmmAuto) {
-                const PrintConfig* print_config = m_print_config_ptr;
-                if (!print_config && m_print_object_ptr) {
-                    print_config = &(m_print_object_ptr->print()->config());
-                }
-
-                filament_maps = ToolOrdering::get_recommended_filament_maps(layer_filaments, print_config, m_print, physical_unprintables, geometric_unprintables);
-
-                if (filament_maps.empty())
-                    return;
-                std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) { return value + 1; });
-                m_print->update_filament_maps_to_config(filament_maps);
+    filament_maps = m_print->get_filament_maps();
+    map_mode = m_print->get_filament_map_mode();
+    // only check and map in sequence mode, in by object mode, we check the map in print.cpp
+    if (print_config->print_sequence != PrintSequence::ByObject || m_print->objects().size() == 1) {
+        if (map_mode == FilamentMapMode::fmmAuto) {
+            const PrintConfig* print_config = m_print_config_ptr;
+            if (!print_config && m_print_object_ptr) {
+                print_config = &(m_print_object_ptr->print()->config());
             }
-            std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) { return value - 1; });
 
-            if (!check_tpu_group(used_filaments, filament_maps, print_config)) {
-                if (map_mode == FilamentMapMode::fmmManual) {
-                    throw Slic3r::RuntimeError(std::string("Manual grouping error: TPU can only be placed in a nozzle alone."));
-                }
-                else {
-                    throw Slic3r::RuntimeError(std::string("Auto grouping error: TPU can only be placed in a nozzle alone."));
-                }
-            }
-        }
-        else {
-            // we just need to change the map to 0 based
-            std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) {return value - 1; });
-        }
-    }
-    else if (nozzle_nums == 1) {
-        filament_maps = m_print->get_filament_maps();
-        filament_maps.resize(number_of_extruders, 1);
-        bool invalid = std::any_of(filament_maps.begin(), filament_maps.end(), [](int value) { return value != 1; });
-        if (invalid) {
-            assert(false);
-            std::stringstream sstream;
-            for (size_t i = 0; i < filament_maps.size(); ++i) {
-                if (i != 0)
-                    sstream << " ";
-                sstream << filament_maps[i];
-            }
-            BOOST_LOG_TRIVIAL(error) << "The filament_map of single printer is invalid. filament_map = " << sstream.str();
-            std::fill(filament_maps.begin(), filament_maps.end(), 1);
+            filament_maps = ToolOrdering::get_recommended_filament_maps(layer_filaments, print_config, m_print, physical_unprintables, geometric_unprintables);
+
+            if (filament_maps.empty())
+                return;
+            std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) { return value + 1; });
             m_print->update_filament_maps_to_config(filament_maps);
         }
         std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) { return value - 1; });
+
+        if (!check_tpu_group(used_filaments, filament_maps, print_config)) {
+            if (map_mode == FilamentMapMode::fmmManual) {
+                throw Slic3r::RuntimeError(std::string("Manual grouping error: TPU can only be placed in a nozzle alone."));
+            }
+            else {
+                throw Slic3r::RuntimeError(std::string("Auto grouping error: TPU can only be placed in a nozzle alone."));
+            }
+        }
+    }
+    else {
+        // we just need to change the map to 0 based
+        std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) {return value - 1; });
     }
 
     std::vector<std::vector<unsigned int>>filament_sequences;
@@ -1173,7 +1153,7 @@ void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first
         first_layer_filaments = m_layer_tools[0].extruders;
 
     // other_layers_seq: the layer_idx and extruder_idx are base on 1
-    auto get_custom_seq = [&other_layers_seqs,&reorder_first_layer,&first_layer_filaments](int layer_idx, std::vector<int>& out_seq) -> bool {
+    auto get_custom_seq = [&other_layers_seqs, &reorder_first_layer, &first_layer_filaments](int layer_idx, std::vector<int>& out_seq) -> bool {
         if (!reorder_first_layer && layer_idx == 0) {
             out_seq.resize(first_layer_filaments.size());
             std::transform(first_layer_filaments.begin(), first_layer_filaments.end(), out_seq.begin(), [](auto item) {return item + 1; });
diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index 8c8dfb7c45..d8304b624d 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -2115,36 +2115,34 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
         if (this->config().print_sequence == PrintSequence::ByObject) {
             // Order object instances for sequential print.
             print_object_instances_ordering = sort_object_instances_by_model_order(*this);
-            if (m_config.nozzle_diameter.size() > 1) {
-                std::vector<std::vector<unsigned int>> all_filaments;
-                for (print_object_instance_sequential_active = print_object_instances_ordering.begin(); print_object_instance_sequential_active != print_object_instances_ordering.end(); ++print_object_instance_sequential_active) {
-                    tool_ordering = ToolOrdering(*(*print_object_instance_sequential_active)->print_object, initial_extruder_id);
-                    for (const auto& layer_tool : tool_ordering.layer_tools()) {
-                        all_filaments.emplace_back(layer_tool.extruders);
-                    }
+            std::vector<std::vector<unsigned int>> all_filaments;
+            for (print_object_instance_sequential_active = print_object_instances_ordering.begin(); print_object_instance_sequential_active != print_object_instances_ordering.end(); ++print_object_instance_sequential_active) {
+                tool_ordering = ToolOrdering(*(*print_object_instance_sequential_active)->print_object, initial_extruder_id);
+                for (const auto& layer_tool : tool_ordering.layer_tools()) {
+                    all_filaments.emplace_back(layer_tool.extruders);
                 }
+            }
 
-                auto used_filaments = collect_sorted_used_filaments(all_filaments);
-                auto physical_unprintables = ToolOrdering::get_physical_unprintables(used_filaments, &m_config);
-                auto geometric_unprintables = ToolOrdering::get_geometrical_unprintables(get_unprintable_filament_ids(), &m_config);
+            auto used_filaments = collect_sorted_used_filaments(all_filaments);
+            auto physical_unprintables = ToolOrdering::get_physical_unprintables(used_filaments, &m_config);
+            auto geometric_unprintables = ToolOrdering::get_geometrical_unprintables(get_unprintable_filament_ids(), &m_config);
 
-                std::vector<int>filament_maps = this->get_filament_maps();
-                auto map_mode = get_filament_map_mode();
-                // get recommended filament map
-                if (map_mode == FilamentMapMode::fmmAuto) {
-                    filament_maps = ToolOrdering::get_recommended_filament_maps(all_filaments, &config(), this, physical_unprintables, geometric_unprintables);
-                    std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) { return value + 1; });
-                    update_filament_maps_to_config(filament_maps);
+            std::vector<int>filament_maps = this->get_filament_maps();
+            auto map_mode = get_filament_map_mode();
+            // get recommended filament map
+            if (map_mode == FilamentMapMode::fmmAuto) {
+                filament_maps = ToolOrdering::get_recommended_filament_maps(all_filaments, &config(), this, physical_unprintables, geometric_unprintables);
+                std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) { return value + 1; });
+                update_filament_maps_to_config(filament_maps);
+            }
+            // check map valid both in auto and mannual mode
+            std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) {return value - 1; });
+            if (!ToolOrdering::check_tpu_group(used_filaments, filament_maps, &m_config)) {
+                if (map_mode == FilamentMapMode::fmmManual) {
+                    throw Slic3r::RuntimeError(std::string("Manual grouping error: TPU can only be placed in a nozzle alone."));
                 }
-                // check map valid both in auto and mannual mode
-                std::transform(filament_maps.begin(), filament_maps.end(), filament_maps.begin(), [](int value) {return value - 1; });
-                if (!ToolOrdering::check_tpu_group(used_filaments, filament_maps, &m_config)) {
-                    if (map_mode == FilamentMapMode::fmmManual) {
-                        throw Slic3r::RuntimeError(std::string("Manual grouping error: TPU can only be placed in a nozzle alone."));
-                    }
-                    else {
-                        throw Slic3r::RuntimeError(std::string("Auto grouping error: TPU can only be placed in a nozzle alone."));
-                    }
+                else {
+                    throw Slic3r::RuntimeError(std::string("Auto grouping error: TPU can only be placed in a nozzle alone."));
                 }
             }