This seems to be an issue that many people are experiencing. All I can suggest is to send a ticket to GOG Support.
You can do so at this link. I am sending them a request as well and will share what I find. Be sure to do the same if you hear back from them before me.
EDIT: I reached out to forum moderator
JudasIscariot and he said that GOG Support is aware of the issue and is working on getting it sorted out. They do not have an estimated time for resolution yet, but they will contact everyone who has been affected once they have a clearer plan for how to handle this. Please. just try to be patient for the time being.