Experienced same problem after installing WatchOS 7.2 beta 2.
Reinstalled one missing app (all were gone) via "App Store" app on the watch. Had to introduce my Store pasword on the watch. After this I managed to sync apps again via the iPhone Watch app.
pareep
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution