If the Xbox sync button is not working, replace the controller batteries first and see. This article lists some fixes that will help you.

You may ran into issues with your Xbox Series X controller from time to time. Here's a few troubleshooting methods to get you back to gaming ASAP.

If compressed air doesn't work, then you'll need to clean the Xbox controller buttons with a cotton swab and rubbing alcohol. To clean sticky buttons on your Xbox controller: ...