I also have problems with this "bid for upgrade". on the outbound my travel partner and I were in the same PNR. bidding did work perfectly. we even won the bid, but could not fly due to the storms in amsterdam.
we were rerouted and our PNRs split.

for the inbound I cannot place a bid for both of us because we are now in different PNRs. the idea posted by the facebook team was to bid individually for each of us. I started doing that with my PNR - it did work, I wanted to bid for my travel partner afterwards and get shown an "technical error - error code 1000" - bidding does not work.

now I am stuck with one placed bid and one passenger not able to bid where in the end one of us could be upgraded and the other one has to stay in coach

let's see whether they can fix the issue. still 7 days until the departure