Frustrating ISO issues

I’ve got a PSP 1000 running 6.61 Pro-C and I can’t for the life of me get any iso files to show up (or show up not corrupted). I can get eboot games to run all day (as long as they aren’t ps classic files) but not the iso files.

I get the iso extracted and place them in the /iso folder in the root menu but when I open my psp the game doesn’t show up or shows up as corrupted. I’ve tried so many different files and always the same result.

Any help?

edit to add that I’m running the pro-c in permanent so to my understanding I shouldn’t have to flash every time. Although I have tried this too.