Try this, bypass the amp and then list all the same info you listed above. The amp could be hiding the real problem. We find MANY intermittent sync issues due to amps. I will check back later for the results. I suspect we will see one of those parameters will be out of spec or nearly out of spec without the amp in place. Did you have this problem BEFORE they buried the drop?
This is CABL.com posting #173906. Tiny Link: cabl.co/mTo6