How to "delete all synced data" under 13.3.1?

Sync has stopped working yet again on 13.3 and upgrading to 13.3.1 doesnt' fix it. Strangely, edits of existing photos in the sync'd folders seem to be migrating to sync over, but adding new photos to folders with sync turned on doesn't result in the photos appearing there. I have tried the below with no changes.:

1. Rebuild sync data (before I saw the message not to do so from Adobe... this used to be my first troubleshooting step so instinctively went for it).

2. Made a microadjustment of +1 contrast on one photo and then did "sync settings" and copied that single adjustment to ALL photos. This virtually ALWAYS worked to "kick in" the syncing feature in the past.

3. Deleted all photos from sync'd folders then added them back. The "new" photos (added since whenever this problem started) did not show up after all was sync'd again.

I thought of just deleting all sync data as they say you can do in the Adobe Prefs pane, but says to do online. There used to be an option under your profile pic online to delete your sync data. That is now gone. 

So.... how does one delete all sync data under 13.3.1 to see if that works in the troubleshooting process?