Upgrade tonight from EWR to SJC was very interesting. Always ranked first on the list and two phone agents kept telling me I was the last one.
Then approximately T-2 (the time I recently found a lot of upgrades cleared at that time), I saw the name right after me disappeared, and the last seat in F got filled nearly at the same time. So there are many possibilities, maybe he/she did a buy-up to secure F, though I think it is not unreasonable to assume that the upgrade processor broken?
Hopefully the PC seat I had still has the middle seat empty till the boarding time (in 45 minutes)..