Trinity crossbow

[Kuffen]

Hey,
My mate pointed out that i dident have the trinity crossbow aschivement.
I have lvled up the crossbow to +20, we played 3 player.

He got the achivement, but not me (cant check the third cus hes hidden his achivements on steam). We think it might be a bugg that he picked it up and we got it but not the achivement.

But something seems to be not working with the achivement.
Anyone know a fix for this? Farm all of them again so another one can pick it up or some other fix?

[Kuffen]

Solved? Started the game -> touched the stone and got the achivement.