Thanks for the info so far. I chatted on WA and of course they can't see the award inventory in any class (for BLQ-HEL) that IS available online. So they are sending it to back office for assistance. They didn't definitively answer my question of whether it was possible, as they needed the space first.

Related question. My husband has 2 SH upgrades expiring 12/22 that we want to use on these flights. I asked the WA agent if expiring 12/22 means I still have the ability to use them tomorrow (12/22) after they let me know what they can do. They said not to worry, that "our team can in problematic situation make exceptions on extending the voucher expiration". But I'm actually still concerned that if the certificates are actually unavailable tomorrow, we'll run into the same situation where I COULD have upgraded them online, but not with an agent who is extending the validity. Long way of asking... if it says expires 12/22, can I USE them on 12/22?