Having spent a couple of hours on the phone with Tech Support I'm sharing this to see if others are having the same unresolved problem.
If I make a change on Ancestry Web then it syncs to FTTM2 no problem.
If I make a change on FTTM2 it does not sync to Ancestry Web.
In all cases its says its synced, but the data does not change if its newer on FTTM2.
Tech support seems at a loss to explain this.