Originally Posted by
Repooc17
Unfortunately, it is very much par for the course to move down the list, no matter what level you are. However, when people pay for upgrades, if they are already on the list ahead of you, your position on the list would move up. If they are behind you, your position would not change.
You are seeing your position going the wrong way due to new passengers being added to the flight with higher status and/or same status as you but higher fare bucket.
Or, for complimentary upgrade (CPU) routes only, applying an upgrade instrument where previously they had been hoping for a CPU. For the OP: CPU routes are domestic and short-haul international routes, excluding Hawaii (beyond California) and SFO/LAX-EWR.
In general, though, the most frequent reason is exactly what you have listed: someone moving onto the flight, either by changing to it or buying a new ticket.