Loading Screen System (Level Transitions w/ Progress)

If your GameMode derives from GameModeBase (the simplified class that Epic added at some point), it won’t have “Delayed Start”, that’s ok, just ignore that.
However, you will only need one Game Mode, not two - check “GameMode Override” in “WorldSettings” with your Persistent Level open and assign the one you need for your game.
Make sure “Start Players As Spectators” is enabled in that GameMode.

Instead of enabling “Start Players As Spectators” you can as well set the DefaultPawnClass in your GameMode to “SpectatorPawn” or even to “None”.