diff --git a/src/libslic3r/PresetBundle.cpp b/src/libslic3r/PresetBundle.cpp
index e09db358ac8..2a301eef9bf 100644
--- a/src/libslic3r/PresetBundle.cpp
+++ b/src/libslic3r/PresetBundle.cpp
@@ -3106,6 +3106,12 @@ void PresetBundle::get_ams_cobox_infos(AMSComboInfo& combox_info)
         auto  filament_changed     = !ams.has("filament_changed") || ams.opt_bool("filament_changed");
         auto  filament_multi_color = ams.opt<ConfigOptionStrings>("filament_multi_colour")->values;
         if (filament_id.empty()) {
+            // keep index-alignment with filament_ams_list so that callers using the
+            // returned vectors by position (Overwriting mode) don't see a shifted index
+            combox_info.ams_filament_presets.push_back("");
+            combox_info.ams_filament_colors.push_back("");
+            combox_info.ams_multi_color_filment.push_back({});
+            combox_info.ams_names.push_back("");
             continue;
         }
         if (!filament_changed && this->filament_presets.size() > combox_info.ams_filament_presets.size()) {
diff --git a/src/slic3r/GUI/DeviceCore/DevMapping.cpp b/src/slic3r/GUI/DeviceCore/DevMapping.cpp
index af3539f3728..93aaec37699 100644
--- a/src/slic3r/GUI/DeviceCore/DevMapping.cpp
+++ b/src/slic3r/GUI/DeviceCore/DevMapping.cpp
@@ -141,12 +141,15 @@ namespace Slic3r
                     if (tray_index == exclude_id[i])
                         continue;
                 }
-                // push
+                // skip empty / placeholder slots: is_tray_info_ready() returns false when
+                // color/type are cleared. Including them would add an entry with id=0
+                // to tray_filaments, causing the distance-map to store tray_id=0 for
+                // that slot and then map real project filaments to the empty placeholder.
+                if (!tray->second->is_tray_info_ready())
+                    continue;
+
                 FilamentInfo info;
-                if (tray->second->is_tray_info_ready())
-                {
-                    _parse_tray_info(ams_id, tray_id, ams_type, *(tray->second), info);
-                }
+                _parse_tray_info(ams_id, tray_id, ams_type, *(tray->second), info);
 
                 //first: left,nozzle=1,map=1   second: right,nozzle=0,map=2
                 bool right_ams_valid = ams->second->GetExtruderId() == 0 && map_opt[MappingOption::USE_RIGHT_AMS];