Best way to test for issues is to try different versions of adrenaline, as well as official psn games from ps1 converted ones. To be honest i always had the idea that the reason why some games aren't playable on psp or made for ps1 classic in the first place was the game couldn't handle it. Playstation made a general purpose emulator unlike nintendo and is virtual console which gets updated to support the required games in the first place. Some games just may not handle it properly, which could explain why some games don't exist on psn in the first place.Ah,i was doing it completely wrong then. I did have a similar issue when playing Tomba 2. There's this minecart racing minigame which was completely impossible. No matter how much i tried i couldn't get close to beating it. Chalked it up at the time to being because of my skills but maybe its cause of a timing issue. Rest of the game was fine though, worked far better than it ever did on psp.
I did try bust a move 2 US again in practice mode and i think it has the same issue. still not 100% sure its not me though
Is just a speculation i had so perhaps is something to do with it. Incompatibility issues are natural perhaps.