Love your app except wish it had a more intuitive feel, instead of having to look for the +Add button on the right, show the folder Explorer like view of the C drive on the left (so we can see and expand the Music folder on our PC and keep it open) where you show Categories and Playlists below it, that would make for a natural left to right (top to bottom) work flow of moving files from your computer to the iphone
Please do the following:
Search for Device manager -> Universal serial bus devices -> iPod (your device) -> Properties -> Change settings -> Update driver (or Roll back driver) -> Browse -> show drivers on my PC -> Select usb mass storage device (or Apple ipod usb driver).
If the solution above did not help, refer to this troubleshooting guide for iPod corruption errors:
https://www.copytrans.net/support/how-to-fix-ipod-corruption-errors/