Hey Vince, what OS are you on?

I just tried for sanity, achievements do unlock properly, do you maybe have an antivirus that is blocking the exe? Potentially bitdefender! An easy way to test this is start a new game and pick whatever choices till you leave JayV that unlocks 1 achievement no matter what.

If the game is not running with GOG Galaxy open, it won't be able to register any achievements, that's how that part works!

I didn't mean to insult you, I'm sorry you received it that way, there's a probability that the gog galaxy related dlls are somehow blocked [windows tends to block dlls for unknown reasons].

I'm trying to help, genuinely. Sometimes the solution is something easy that players miss out, not everybody is fully technologically adept to how GOG galaxy works, but this went through GOG QA (on Win11) as well and had no issues, so it's something else.

I work for Wadjet Eye Games, and I'll happily help however I can.
I'll suggest a few things just to rule them out!
1) Make sure OldSkies.exe is not blocked by a firewall
2) check agsgalaxy.dll and Galaxy.dll (they are installed where the OldSkies.exe is) by right clicking them -> properties and checking if either of them have the option to unblock. Same for agsshell.dll
3) Try disabling the GOG galaxy overlay for the game, maybe.
4) Blackwell uses the exact same plugin, so this is weird for sure, I'm trying to see why this is troubling you!
5) Can you try logging off GOG Galaxy if possible, closing it entirely, then logging back and trying it again?

Meant no disrespect or to convince you that there is no problem, of course there is, I'd love to help you, and I'm sorry you're dealing with this issue.

Forgot to ask something important too, does the Overlay show up? [I understand it doesn't because achievements don't unlock, but it should appear on the bottom right as you start the game, a few seconds]