My guess is it’s just super slow. Some of my roms are on a USB HDD attached to my pi. That HDD is formatted in such a way that windows can’t see it. Since all my PCs are windows machines, I have to transfer roms to the HDD via SSH to the pi. The USB transfer speed is snail-like. lol
I’ve spent many hours on google looking for a way to speed it up, but nothing has worked.
^^ my other hobby