Don't know what happened but my all Steam achievments are gone from the recent bookmark.
The only achievments that are on Gog Galaxy 2.0 are from other platforms (Gog, Origin, etc)

GOG Galaxy is still in development so such bugs are frequent.

Try seeing if restarting your computer might help.

I'm having issue with syncing of Steam achievements as well, some games sync but some games don't somehow. It started a few days ago.

Same for me.

Same for me.

I have tried to disconnect/connect steam integration and doesn't work. Now I have almost every steam game with no achievements.

Looks like this is a widespread issue.

https://github.com/FriendsOfGalaxy/galaxy-integration-steam/issues/92
https://github.com/FriendsOfGalaxy/galaxy-integration-steam/issues/91

I don't think this is the plugin's fault as it was working fine for months, probably something changed on Steam or GOG backend.

Still broken right?