Full Screen does not work! (macOS Sierra)

When going to full screen, the screen just goes white and the only way to recover from this is to restart the app and open the movie……and then DO NOT GO TO FULL SCREEN MODE. That makes it pretty much useless :-(

Details: playing *.mkv files on macOS Sierra on 2012 Mac Mini.

ToscaZuzu about MPlayerX, v1.0.14