I was just about to make a thread on this exact same issue. :)

I’ve also tried everything I can think of to get into the test/service menu on mame4all-libretro. I prefer to use retroarch for the shaders (the mame4all scanline shader is pretty poor) and for the extensive settings compared to mame4all.

The cave shooter, ESP Ra.De. won’t progress past the initial mandatory test/service screen because I can’t exit it. All other cave shooters I’ve tried also start with the picture flipped upside down, which is something else that I need to get into the service/test menu for.

I can also confirm that anything past the first Mortal Kombat, doesn’t work on mame4all.