This is embarrassing. The problem was...my wireless mouse had turned on in my bag unknowingly and was "active" thus causing the screen to show the control.
Love this app, and glad to know this was wholly user error!
Been running Mac v3.0.8 for a while with no issue. Upgraded to Mojave (10.14.6) this weekend on MacBook Pro Retina 15 inch, and fullscreen mode has the player controls popping up every couple seconds, fading out and popping back up. Very annoying. Help!!