GPU Priority Waitlist not converting to active Stand By?

Last November I was booked for EWR>HKG and my 1K GPU was attached to my fair - I was told I was first in line on the priority wait list for a coach to biz1st upgrade at the time of booking (8 months in advance) and every month until day of departure.

Upgrade did not clear before check in- checked in 24 hours early.

The online stand-by list showed names being added and added for BusinessFirst upgrades, but my name never appeared on the list.

I kept calling back and was getting mixed stories about not showing me checked in, or showing me checked in and first on the wait list, but i still never saw my name on the "Customers awaiting upgrade" lists.

My connecting flight to EWR got in late and I got to the gate for the HKG flight with about 35 minutes to spare.

The screen showed that 12 people had been upgraded and about 20 had not been upgraded. My name appeared on NEITHER list.

Obviously I had checked in - I had a boarding pass for both flights.

The gate agent looked me up and found my name on some "other" list, and fortunately a missed connection kept one seat open which he gave me.

Anyone know why this happened and how I can prevent it from happening again? I am on the same itinerary this November.