Sorry to step in, but it could also be your console.
With the MegaSD, I was freaking out at first because in my main Megadrive MCD games would freeze, display graphic artifacts or not even boot at all.
Turns out, that MD which works flawlessly with original MCD+32X and never had a single issue - it was the culprit. Tested other 3 MDs and they worked like charms with MCD games on MegaSD.
So maybe my MD would need a recap (I guess?) so your PCE may need that as well. Or, your RGB mod is interfering somehow.
SSSD3 is very sensitive, and as a matter of fact those (like me) who have a Coregrafx have several issues with Arcade Card games.