@red_trev I’m currently in the exact same situation. Is displaying emulation station, as well as all emulators run through it, on the second display even possible? Sorry for replying to this old post, but I have searched far and wide without coming across any solutions (that doesn’t require x session, xrandr etc...).
What game(s) have you tried? It could be a corrupted ROM, so try a few different games or try to find another copy of the game.
Have you tried to remove the redream package and re-install from the latest binary?
Also have you tried using the lr-flycast or Reicast emulators to run the game instead? Both can be found within the optional packages menu. When launching the ROM, hit a button to choose which emulator to use(once you have installed them). All three emulators run well on my RPI4 4Gb at stock speeds.
Only other thing is to think your pi is throttling, have you any heatsinks/cooling? Are you using a case?