Pro Pinball series is have graphical issues when shoulder buttons (L1/R1) are press

All Pro Pinball games: Big Race USA, Fantastic Journey, Timeshock!, and The Web, are having graphic "glitches" when the shoulder buttons (L1/R1) are press. The screen will blink, everything will freeze when R1 is press, the table will say "tilt", but all the flipper will freeze. Not sure if this is actually how it works or is it a bug. And the ball will just "free fall". Don't have a PSX at the moment to verify the accurate behavior, and almost all software emulators are having problems with these games too. So really don't have a baseline on how things should behave.