source/blender/windowmanager/intern/wm_files.cc

@@ -2443,6 +2443,11 @@ static int wm_userpref_read_exec(bContext *C, wmOperator *op)
     U.runtime.is_dirty = true;
   }
 
+  /* Ensure the correct icon textures are loaded. When the current theme didn't had an
+   * #icon_border_intensity, but the loaded theme has, the icon with border intensity needs to be
+   * loaded. */
+  UI_icons_reload_internal_textures();
+
   BKE_callback_exec_null(bmain, BKE_CB_EVT_EXTENSION_REPOS_UPDATE_POST);
 
   /* Needed to recalculate UI scaling values (eg, #UserDef.inv_dpi_fac). */