I had a similar strange occurrence a little over a year ago, companion (no status, but linked) got upgraded ahead of me, while I was still in the back. Even at T-24 with J3 or J4, I wasn't upgraded, eventually ending #1 at the gate with zero available. My thought was lower status people got upgraded ahead of me, (or 4 people could've paid for the upgrade). But the fact my non-status companion got upgraded ahead of me, and I wasn't, even with open seats, I chalked it up as some system error/glitch.