This is probably too late to help the above, but for anyone reading this here you go.
The issue is storing objects(actors) in a save game file. IE actor variables that have a reference to an actual actor in game, on a map.
This may sound like it should work, and it can and does, but for whatever reason UE forgets them when loading that save file, from time to time. Then you will get the None.None errors.
I’ve found the best remedy is to create GUID’s for your actors that you store and save their GUID’s as well. So if the reference to the actor goes missing, you can recreate the reference with a find all actors and search for the GUID(s) of the missing actor(s) and resave them.