Once Unreal Editor has crashed, I sent logs and restarted the editor. After restart all my blueprints stopped working except a GameMode blueprint (I connected Print String node to Tick event of every GameMode classes, but strings were printed only from the GameMode bp). Even level bp didn’t tick.
I tried to create a new project and migrate content, to create new level/new gamemode, have checked class assignments in gamemode and World override, tried to recompile it, but it didn’t work.
Tried to set both default GameMode and BaseGameMode and blueprints started to work (but with errors - casts fail).Then I created new GameMode to assign classes one by one. It turned out that assigning custom GameState class is somehow breaking GameMode class that even setting default GameState doesn’t make it work. But if set GameStateBase it begins to work.
First time I created a custom GameState derived from GameState, when I noticed that, I solved the problem by deriving from GameStateBase. Though it isn’t clear for me why GameMode breaks completely if derive from GameState.