Apple Music not working after update

Hi, Alma622.

We know your time is valuable, and we appreciate you taking the time to post in the Apple Support Communities.

If we understand correctly, you weren’t able to play full songs in Apple Music after updating your iPhone XR to the latest iOS version. Are you still experiencing this? If you are, we’d like to see how we can help. 

1. Force quit the Music app and reopen it.
2. Check for updates (we should be on iOS 14.2.1 today) again.
3. If you're fully updated, go ahead and try fully restarting your iPhone.
4. Try removing the Music app and reinstalling it.

This article doesn't address the exact issue you're experiencing, but the first four steps will outline the best ways to work through each of our suggested steps:

If an app unexpectedly quits, stops responding, or won’t open - Apple Support

If you’re still only seeing previews for your songs, check to see if they are previews from songs that you have downloaded on your iPhone or that you’re streaming directly from Music. If it’s a streaming song, try downloading it to see if that impacts your ability to listen to the entire song. If it only happens when streaming, you might also try listening on a different network connection (e.g. test on both Wi-Fi and your cellular data connection). 

We look forward to learning about your progress.

Warmest Regards.