We had one of our regular customers bemoaning this issue yesterday on the phone. They say it only started with all the changes to the collection only rules etc a few weeks ago. More worryingly they say the countdown clock on auctions changes it’s time when the screen changes red to green. For them the auction clock is adding their end up to 45 seconds to an auction but it’s not letting them bid as the auction has obviously finished!
I don’t know if this latter part is the same for you op? Would be interested if it was as something is really not right with eBay at the moment when it comes to auctions.