Gamemodes custom pawn switches to default pawn

Im using the thirdperson template and I have a gamemode blueprint with my custom pawn ‘ThirdPersonCharacter’,
when performing an ‘Open Level’ operation the pawn switches to default pawn.

(Note this only happens when launching the game/Packaging the game. Not in PIE)

The world settings on both levels are at this point using my custom gamemode, and have the default pawn class set to ThirdPerson character.

Would there be any reason why it switches to the DefaultPawn?