I started having this problem a couple months ago - not sure what's different...
I can add star ratings to my tracks but the next time I load up WMP (12) they're gone until I play the track again. After the track finishes playing, the rating appears. Skipping to the next track does not work - I have to let the current track finish then wait for WMP to automatically move to the next. After it moves to the next track, the correct star rating appears.
Therefore, I can't sort by star rating on any tracks I've added in the last couple months. This is a major problem for me.
I have WMP set to "Maintain my star ratings as global ratings in files". The star ratings appear correctly in Windows Explorer. I've been doing this for years and all my star ratings are intact but WMP does not show them for the tracks I've added in the last couple months.
How do I fix this problem?