There are cases where changing the Role and RemoteRole of a Pawn doesn't get properly replicated. The underlying issue has to do with ScopedRoleDowngrades and Shared Shadow State.
A workaround is to set the cvar net.ShareShadowState to 0, though this will likely negatively impact server performance.
*Note:* Order of client connection *is* important.
Only the currently possessed pawn has Role AutonomousProxy on the second Client, all other pawns are SimulatedProxy.
Any pawn that was ever possessed by the second Client has Role AutonomousProxy.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-54477 in the post.