Try contacting HP directly via Technical Support and see if they have any updates. Firmware updates can only come from HP, nothing we fellow users can do about it.
As long as your printer is covered under the warranty then HP should be able to do something. Perhaps they have a firmware patch that is available but not published to the public because so few rely on that specific feature. At the very least contacting them would start and official Incident that they can send to the engineers. HP will continue to support a particular device until it goes End Of Life, which should be a while for your printer model.
Keep us posted and let us know if you learn anything new.