My guess would be either CSUR Loader, CSUR Toolbox or both of them, since the rest of them should work just fine in the map editor afaik.If you are using a lot of custom assets, it could be you are running out of memory. Do you get a crash with a pop up saying something like "Oops the game has crashed"?
This thread was added on June 03, 2020, with posts from Avanya.