Songs load according to Windows Media Player, but do not appear in Clip + menu

There is no album art in any of the album folders (assuming that is where it would be), as there were all synced via WMP. Could you guess how much I would gain if I deleted all the album artist tags? I could do it fairly efficiently using mp3tag but it would still be quite time consuming, and I have already spent way tto many hours chasing this issue.