Until this issue is not fixed (I am waiting for to give him access to my project), I recommend two precautions to avoid the bug:
- Never save your map after compile a blueprint which have an instance in the map (even if this blueprint doesn’t suffer with the issue).
- If you are in doubt if you can save the map or not, select an actor which frequently loses it’s properties and duplicate it. If the properties are all correctly duplicated, then your map is ok and can be saved; otherwise, close without save and reopen the map.