I may be wrong, but apparently you can’t set the rotation of a possessed pawn directly with “set actor rotation”; you must instead apply the rotators from your facing array to the player controller via Set Control Rotation.
I suppose you could also use a separate camera and unpossess the player pawn while keeping the camera active, before repossessing it after the rewind function ends; in that way you should be able to use Set Actor Rotation.
https://forums.unrealengine.com/t/set-actor-rotation-doesnt-work/314081/6