So I reinstalled BG3 through Galaxy app after changeing some PC parts. Every time I try to launch the damn game the launcher nags me about a data mismatch. I tried to check the file integrity two or three times and each time Galaxy downloaded a 175MB file. BG3 launcher still showed data mismatch error. Now the weirdest part is that GOG Galaxy shows that I have 100% achievments while I hadn't even left the first act. I uninstalled the game, reinstalled GOG Galaxy and nothing changed.

q1 - what pc parts?
q2 - how many accounts have you got?

My achievements are also broken now. I only see the normal "missing image" icon. This sometimes happens to new achievements on many games, but now all broke simulatenously and the text disappeared too. I can just see a single "-" or "."

PS "My progress" is actually fine, only "overview" is broken. in my case.

Processor and one account So it can be a Galaxy app's issue not connected to BG3? Interesting

I just upgraded GOG Galaxy and I think I am seeing the same thing as Zyrxog. I see the correct progress 65% and all the achievements I have completed. But I dont't see the achievements (normally greyed out) yet to be completed.

Edit
This only to applies to BG3 as for other games achievements display correctly.

I have the same.

i can see why cpu would cause issues yes

a fresh copy of Windows then all your software is the way i would move forward

I also have a similar issue.
The achievements say 100% when I know that's not true and the icons for them are all 404 images. The unearned achievements are missing completely.

guys achievements are different things and not really what this post is about however yes the Gog servers are currently busted / not talking to other servers so that effects 'achievements' in game like fuckpuck, Stellaris or Bg3 where the other server is in charge of tracking who got those achievements

Gog is well aware achievements and other things like cross saves are busted and its at their end but i'm not aware of any plans to fix it or even if they give a shit

I'm experiencing the same thing with achievements.

Good morning o/

My achievements are also broken. Additionally, it's displaying 100%, which is definitely not accurate. It should be around 50%, not 100%. The icons are also broken. Hopefully, this gets fixed soon.

Regards,
melcom

This is by no means only affecting the achievements of a single game: it's a major issue with the Galaxy client and everytime this happens neither the profile page, nor the activity feed is working anymore inside the client.
That means it affects all games associated with one GOG account inside Galaxy (through all connected platforms) and with both Mac and Windows versions of the client.

Outside (like on the web profile page, the one without all those "integrations" like Epic and Xbox) everything is working fine and this is also where you have to go to fix the problem because hiding the game from your account doesn't help either: what you have to do is instead go to this still working activity feed. There you have to manually remove all affected achievements and confirm those removals.
Every achievement that's so to speak "broken" inside the client but working on that page. Entries regarding time are not triggering the effect and should not get removed, really only the "broken" achievements.
In my case regarding "Baldur's Gate 3" it was only one single achievement causing the trouble: this way you still won't get rid of the wrong "100%" on the game's client page but at least everything else is working again.
In my opinion this issue is otherwise rendering your account completely useless inside the client. Throughout September I completely lost my overview because of this and some "broken" achievements of the game "Rise of the Triad - Ludicrous Edition": after writing many mails and providing multiple screenshots as proof (like the ones in this thread), GOG support granted me an extraordinary refund.
The solution I'm describing here I just figured out later: "Baldur's Gate 3" is a much bigger game of course, and I hope GOG will now finally patch the client when people are spreading the word about this annoying issue cause what this bug does is basically messing-up your whole account when using the client.

On my profile page, it does show the correct 51% of my achieved achievements so far, but unfortunately, it no longer displays the achievements that are yet to be unlocked. Unfortunately, this doesn't change the fact that we currently can't unlock new achievements in the GOG client because GOG isn't really addressing the issue... they don't even respond when you submit a ticket on the website or reach out to them via Twitter. Truly disappointing. Since I enjoy earning achievements, I'm currently unable to play Baldur's Gate 3.

//EDiT:
Even though there are currently issues with achievements or displaying them correctly, they still seem to be functioning. This means you can still unlock new ones. I just got the achievement for mind reading when I previously used a potion (Mind Reading). I tried the potion in Act III at this circus on a person, and lo and behold, I got the achievement: 'Gedankenleser' / 'No Penny Required.' Check my profile. I just got the achievement moments ago.

Okay, I'll continue playing later :)

Hey o/

I finally received a response to my submitted ticket from GOG after 2 days. And, how could it be any different? Supposedly, I have unlocked all achievements in Baldur's Gate 3, and they don't know how to help me.

I replied asking if they didn't understand my message or my screenshots. Additionally, I once again referred to this forum where we are all currently having issues with achievements or the display showing 100%, but it's incorrect.

I have no idea why we have forums if even the support team doesn't check them, despite the note in the ticket to take a look here.

Hopefully, the achievements will be fixed soon. They can be unlocked, as I mentioned in a post above mine. I tested it. However, they are not displayed under "Activity," and under "My Progress," missing achievements are not shown. Since ONLY the unlocked achievements are displayed, some of us end up with this 100% issue.

Regards,
melcom

//EDiT:
Sorry for my poor English ...

I also have missing icons "overview" and if i go check the "my progress" it says 100% complete and only shows those i have unlocked so far.