GOG does not have the latest version of the game and because of that, cross platform compatibility has broken for anyone who has already updated. When is GOG going to get 2.0.8? My friends on Steam are all playing together while im stuck on 2.0.7 because I cant see any games in the loby unless they are on 2.07 I have tried to update about 100 times, tried redownloading the software, no changes...

I have exactly the same issue, this is good reminder to not buy anything multiplayer on GOG in a future.

Day 2, still stuck on 2.0.7. I enabled experimental and it downloaded 2.0.9. WTF!?!?!?!? Turned off experimental, back to 2.0.7. GOG for whatever reason doesnt have this version and I am tired of waiting. Looks like im going to just switch my account over to steam and request a refund here and buy there. I learned my lesson.

I just use the in game updater

I tried that as well. It keeps telling me there are no updates available. I ended up buying the DLC on steam and asking for a refund here. I couldnt see my friends games hosted on 2.0.8 and my friends couldnt see my hosted games.

The ingame updater very definitely works in principle. If you previously tied your Factorio key to the Wube account, you just need to attach the new Space Age key to the same account.