It seems there is new rule in AY business cabins. At least 1 business class seat must remain empty.
My HEL-BKK did not clear at T37. It was showing availablity in J&C some shortly before that and also after, J1C1... etc, so I WhatsApped them that I would like to get upgrade or at least back to the list and they said that there's a new policy that at least 1 J seat at all flights must remain empty. When I challenged them that I see plenty of flights were all J seats are allocated, then she said that that is mistake... Then I called the Platinum line by phone and same message...
Later they followed up with email as well
Thank you for your inquiry and patience.
I requested some additional information regarding the available seat in J-class that must be left empty at all times. As I mentioned in the chat before, this is not an upgrade slot and it cannot be confirmed to any passenger. This seat must be left open in case of emergencies, such as crew transportation or other kind of inner use. In other words, this seat cannot be occupied by anyone outside of Finnair personnel, and therefore it cannot be given to any passenger regardless of their tier-level.
I understand your frustration regarding the upgrade slots, and I am sorry we were not able to provide this service for you on this flight. Hopefully you can us your benefit to some other flight that you have with us in the future.
So, staff upgrades trump over Lumos even at AY per latest guidelines.