Man I’ve spend around 4 hours trying to figure out what the "§ll is going on and this post saved me, thanks so much.
From my side I fixed it by commenting out the initializers for the default pawn class and default hud from the base GameMode. (UE V4.14.3)
AMasterOfShadowsGameMode::AMasterOfShadowsGameMode()
: Super()
{
// Commented out all of this and it just worked again :)
// set default pawn class to our Blueprinted character
//static ConstructorHelpers::FClassFinder<APawn> PlayerPawnClassFinder(TEXT("/Game/Dynamic/Character/Behavior/Character_BP"));
//DefaultPawnClass = PlayerPawnClassFinder.Class;
// use our custom HUD class
//HUDClass = AMasterOfShadowsHUD::StaticClass();
}