I've had something similar.

I cannot remember the exact combination of searches I did, but after using the 'Any Type' search once or twice, clicking on Audio didn't show the correct search details. Instead of showing 'Artist' or 'Title' it just showed 'File Name.' Infact, after that ALL the search types only showed the 'File Name' field.

Sorry I couldn't help anymore.

Cheers
Vaz