Not a War Hammer Achievement.

[Gardol]

I had more than 40k gold but I don't get the achievement, why?
Isn't work?

[SuperPuffer]

Try this.

1. Browse to %AppData%\Roaming\Dwarfs
   
2. Now rename the file achievements.lol to achievements.bak
   
3. Launch the game and collect 40k gold (cumulative - you can spend the gold)

[SuperPuffer]

Another workaround is just playing on a friend's computer who has never played Dwarfs!?

If your friend plays this game on your Windows desktop, but is logged in under their Steam profile, when they unlock a Dwarfs!? or Dwarfs - F2P achievement, it can lock the achivement permanently on your Steam profile for both games.

This was the only way I found to get some achivements on my own profile using my own computer on Steam. The in-game achivements still work, it looks like, but sometimes they look wacky like you have an achievement you don't have.

[CodaMezzo]

This helped me too