Player rotation changing without input immediately after spawning

Please avoid bumping threads more than once a week.

As for the problem, if memory serves, the rotation of the player controller is only set to the player start if the pawn has a player controller when it first spawns.
Since you’re spawning the pawn THEN possessing it with a player controller, the player controllers rotation is probably overriding the pawns.

Try forcing the player controllers rotation as well.