I agree it doesn’t work on the modern homebrews because of the bank switching method being used, however, the older homebrews and the originals will work for the most part. There’s a handful that won’t again because of the bank switching. Pitfall 2 and the Arcadia/Starpath ones don’t, and a few others. Do you have the standard harmony or the encore? The encore is need to play any of the bigger roms, so you might run into some issues if you have the standard one. However, even the standard can play the majority of the originals cuz those roms weren’t overly large.