FYI, Pawns are not instantly possessed by the controller. It takes a few milliseconds. If Show Player HUD is called before possession has occurred the logic flow will fail with accessed none errors.
For quick hack you can add a delay node to give you a few hundred ms for all the possession processes to complete. Typically you’ll see this on the Begin Play node of the player class.
The best approach overall is to Poll all your priority Obj/Comp references. When they are “set” and “valid” then execute chain logic that has such dependencies.