Thanks! Don’t know the reason for the migration stuff. I’ll add removing the cast in Tile_Parent to the list. I’ve found a couple of new problems too. Some of the changes seem to be reverted once the project is saved. The references to self in Unit_Parent are unplugged each time. You can get around this by casting self to Unit_Parent, but this should be unnecessary and gives a warning. It does work as a workaround for now, though.