I add some folder to music library. In windows media player 12 every song has proper info about album, artist et cetera, but when I open metro ui music app (v 1.4.18.0) it show almost every song in category unknown artist with unknown album. I try to rebuild music library using some help from answers.microsoft.com but at the end effect is the same.

Correct me if I am wrong: music library is common to windows media player and music app and info provided from library to apps shoud be the same?

Yes, music library is common to windows media player and music app, and information provided from library to apps shoud be the same.

Keeping your app up to date is one way to make sure that it keeps working. You’ll see a notification in the Store whenever an update is available for your app.

If a license for an app is out of sync with the license installed on your PC, the app might stop working.

If your apps are up to date and the licenses are synced, you can reinstall the app to try to fix the problem.