Photos edited on Lightroom Mobile are not syncing to Lightroom Classic

Other things that could possibly stop sync are lack of available space in the Cloud (although you would have seen the warnings) or sync errors (these can be viewed on Lightroom Web, over to the left).

At a bit of a loss really to pinpoint the issue.... maybe a member of staff can help.

On one of the photos that haven't synced, maybe perform an additional edit, tap force sync, and see if this nudges any movement.

And you're logged in with the same account details?

The only things I can think of are lack of internet connectivity or if Sync has been inadvertently paused (check by tapping the Cloud icon).

Assuming you have Cloud storage, you can check if the photos have firstly synced to the Cloud by checking at http://lightroom.adobe.com/

If they are not there, then the issue is the sync up to the Cloud from Mobile.