I've never known this to happen on VS.
Reason being, is because their Op-Up procedure (from what i've seen in practice) is to allow everyone to check in and only then start shuffling people around if needs be. They will only do a move if it's absolutely necessary and they want to wait for all the variables to settle before doing so.
Here's a related example:
I was on an LAX flight a few of days ago, and I knew they were still selling seats for premium. It was at W5 S4. Seat map in Premium showed all seats assigned, excluding those blocked apart from one middle seat.
I took the opportunity to ask for an upgrade at check in, there had been none in the days and weeks running up to the flight. There was one seat left that they were willing to either take cash or miles for. I opted for miles. I was SEQ 190 out of 210, so very late to check in. At this point, even before I had asked about the upgrade, VS probably knew full well someone was going to have to move out of Premium and into that remaining Upper seat, anybody else would have to be shuffled out of Premium onto another flight, or into Economy.
Fast forward to the flight, low and behold, every seat in Premium is taken - including the one that was originally assigned to me.
Conclusion:
VS will wait to the absolute last minute and do gate upgrades to give them every opportunity to work out the no shows, sell cash or mileage upgrades at either check in or the Clubhouse and only when all options are exhausted, they will pick who moves. This is usually decided by the time the gate opens as whenever an Op-Up happens, the gate agents almost always have your new boarding pass ready to go for when you get the magic beep.
Most of this information is gleaned from gaming the upgrade system on many dozens of VS flights and simply observing as closely as possible, how that process works from the outside.
EDIT: thought the OP was asking about Op-Ups at online checkin, not paid upgrades. My bad.
Last edited by CommanderB on 11 Mar 2019, 19:18, edited 1 time in total.
Fly's a little too much.