Weird because even my craptastic chinese junk tablets work reliably. I also tried androidx86 on my PC but that was a bit glitchy.
Only other thing I can think of is to make sure you are using the right connector and the switch is in the correct position.
you might have been trying to use the ipod socket and switch position. I did that at first. You actually need the same cable as for the PC. A USB type B cable that plugs into the larger square socket in the back of the amp. For a plug like this one
I made the same mistake but just happened to have an old USB printer cable and the OTG adapter I mentioned previously. Was about to give up and thought I'd try the PC side since I had already tested it as a recording interface with my PC. Here's a pic of the 30, you can see the white USB type B socket is labeled Mac, PC, Android.