Solution: Windows Media Player 11 doesn’t update media information on Vista
I’ve been tearing out what hair I have left, trying to work out why the mp3 files aren’t updated when I change the metadata in Windows Media Player 11 on Vista.
I spent hours updating my music metadata, only to find that the metadata isn’t persisted to the underlying mp3 files. I tried using "Apply Media Information Changes" (AMI) but it didn’t seem to make a difference.
As it happens, all AMI does is raise the priority of the background task that persists all the queued media information changes.
But no matter how many times I ran it, and no matter how long I waited, the file metadata was never updated.
The solution, in my case, was to do with permissions: in my set up, the Music folder is redirected to the D: drive. I wondered if that was causing problems for WMP when it was trying to update the files. I loosened up the permissions on the folder, just in case, and hey presto it works! (jeez, do people still say that?)
All I did was give Everyone full control to the Music folder. Then I ran AMI again and all of my metadata was written to the mp3 files.
This is obviously a pretty coarse-grain solution: it would be better to find the exact user that the AMI task runs as and the least privilege it needs. But it’s late, and I’ve had far too much wine. If I find out which user to grant the permission to I’ll be sure to update this post.

November 6th, 2007 at 23:29
I was just working on the same problem when I found your post. Annoying that vista does not give information as to the problem or that there is a problem at all.