1 files changed, 22 insertions, 1 deletions

diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index a92404b2372..29366e3bae5 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -703,7 +703,7 @@ void IDP_WriteProperty(const IDProperty *prop, void *wd)
   IDP_WriteProperty_OnlyData(prop, wd);
 }
 
-static void write_iddata(void *wd, const ID *id)
+static void write_iddata(WriteData *wd, ID *id)
 {
   /* ID_WM's id->properties are considered runtime only, and never written in .blend file. */
   if (id->properties && !ELEM(GS(id->name), ID_WM)) {
@@ -731,6 +731,11 @@ static void write_iddata(void *wd, const ID *id)
       }
     }
   }
+
+  /* Clear the accumulated recalc flags in case of undo step saving. */
+  if (wd->use_memfile) {
+    id->recalc_undo_accumulated = 0;
+  }
 }
 
 static void write_previews(WriteData *wd, const PreviewImage *prv_orig)
@@ -1131,6 +1136,11 @@ static void write_nodetree_nolib(WriteData *wd, bNodeTree *ntree)
   for (sock = ntree->outputs.first; sock; sock = sock->next) {
     write_node_socket_interface(wd, sock);
   }
+
+  /* Clear the accumulated recalc flags in case of undo step saving. */
+  if (wd->use_memfile) {
+    ntree->id.recalc_undo_accumulated = 0;
+  }
 }
 
 /**
@@ -2425,6 +2435,11 @@ static void write_collection_nolib(WriteData *wd, Collection *collection)
   for (CollectionChild *child = collection->children.first; child; child = child->next) {
     writestruct(wd, DATA, CollectionChild, 1, child);
   }
+
+  /* Clear the accumulated recalc flags in case of undo step saving. */
+  if (wd->use_memfile) {
+    collection->id.recalc_undo_accumulated = 0;
+  }
 }
 
 static void write_collection(WriteData *wd, Collection *collection)
@@ -4012,6 +4027,12 @@ static bool write_file_handle(Main *mainvar,
         if (do_override) {
           BKE_lib_override_library_operations_store_end(override_storage, id);
         }
+
+        if (wd->use_memfile) {
+          /* Very important to do it after every ID write now, otherwise we cannot know whether a
+           * specific ID changed or not. */
+          mywrite_flush(wd);
+        }
       }
 
       mywrite_flush(wd);