It looks like sometime around the last AGO update my editor tracking on a AGO HFS stopped working. Times sometimes work but created_user and last_edited_user are no longer being populated. This had been working for over 2 years then suddenly nothing.
In case you don't know already note that AGO uses different tracking names when enabled after a post of data. But if you enable then post it keeps the geodb naming convention. Why AGO and File GeoDBs use diff field names is a mystery to me (and drives me nuts).