Whoo! After 4 days of experimenting and research, I finally got it working thanks to the ideas over at this thread over here
Basically, I needed to use the node “get all active users” (never used that one before!) plugged into “create a local player for platform user”.
But this was not the only issue, as this alone does not give control to the pawn from any other controllers…
So I needed to add a delay in my character BP, BEFORE adding the mapping context for the input controllers.
I’m still unsure why this was necessary to set up like this, as before using “create local player” alone worked great. However I am glad I finally got something working.
Good luck to you if you are facing this issue, and hopefully this thread helps! 