Ok, I'm confused. I went into the directory( which for me is C/Program Files(x86)/GOG GALAXY) and looked into the plugins folder, and there is no subfolder for steam. There is one for EPIC and one for Xbox, but no steam. So I just made one, named it the same as the other two and put the new files in there. Nothing. What am I doing wrong? I reinstalled GOG GALAXY twice now. Anyone?

Trying the suggested solution hasn't worked for me.
And now Ubisoft doesn't work either.
Seems like less and less of the integration plugins work.

You got the folder wrong. It's located in %localappdata%\GOG.com\galaxy\plugins\installed\
Be sure to reinstall GOG as you could have broken a few things messing in the wrong folder. Try to connect to steam with the broken default steam plugin just so that it downloads and installs the broken steam plugin.
Exit GOG client.
Just hit WINkey+s and type %localappdata% in the windows search box. It should take you directly to the appdata\local folder. From there navigate to the gog.com folder and all the folders mentioned above. Search for the steam folder in the installed directory. It should look like steam_bunch of numbers and letters. Delete all the contents from that steam folder and copy the fixed version there. Start GOG galaxy and it should work now.

Hey,it worked! Thank you very much!

Damn THX Bro ! :)

This worked like magic for me

works great, thx

Thank! Worked for me.

Note that with this temporary fix, the Steam integration reverts to Offline mode with every restart of GOG Galaxy. In this Offline mode, the previously imported data (games, etc) should still be present in Galaxy, but will not refresh. Disconnecting and reconnecting your Steam account to Galaxy should reinstate the integration thus importing new data.

From the other thread, there's a proper fix now. Someone wrote a new Steam plugin which does, indeed, work.
https://github.com/ABaumher/galaxy-integration-steam/releases

Now we just need to get that incorporated into Galaxy client so it gets fixed in next update. Any guesses how soon CDPR will do that? Surely by next week?

I followed the instructions in the link exactly. not only did it not work, but now some of my steam games wont boot, even after a full restart, running the games as admin and verifying the file integrity.

Working GOG Galaxy-Steam integration available now, follow the instructions in the Github:

https://github.com/ABaumher/galaxy-integration-steam/releases/tag/v1.0.5-beta

"It works for me".

Ok, I know that's annoying and unhelpful, I saw an error message using their "1 click" script (some file not found) so I used the classic installation method. I also wiped the GOG steamdb as suggested for good measure.

it most definitely DOES work for me .. but it doesn't pick up Steam "last played" stat. You can search and start the game as normal, though, it'll show up in last played afterwards. I can see it does "syncing steam integration" but it doesn't seem to collect this stat.

I can't comment on steam games not working afterwards, "works for me". Although you did specify "some", so perhaps I just haven't found such a game. Then again, the only reason I could think of is that you've got crashed GOG task running on the background or perhaps you got locked out of your steam account, but then Steam wouldn't let you log in before you do 2FA.

It looks like my problem with the last played stat may have been caused by deleting the steam database which they mention as an optional step. Apparently it takes a good long while to update things on the background so I was not seeing the latest games in the list for some time.

I think it works now

works fine thanks - now only ubisoft is missing xD