So, I delete GM and open Unreal Engine, try do touch everything and all works fine, than I reset file which was deleted and can open it and even start game! So, than I save everything and close UE than open project again aaaaand it’s broken again… I just try to open something and UE crashed until I delete GM… I don’t know what to do now… May be something inside of my GM caused this failure… I can share the screenshots of my blueprints, if you want
P.S. Interesting moment but in that iteration of GM “Thumbnail” field, doesn’t appeared.