HBorg Special Not Unlocking [PC]

I believe I’ve managed to bug out my HBOrg special.
Unfortunately while completing the achievement my XboxLive got disconnected and after getting to the disco with the dancing brute I didn’t get the achievement pop.
I reset the game, tried again and unfortunately it didn’t work.

I have since restarted the PC and have attempted the achievement 2 more times, this time on co-op, my friends I did it with again did unlock the achievement in the session I was also in… I’ve also tried being the host and not being the host, just to rule out any bugs, but I’m pretty sure that the error is purely to do with the brief disconnect I had originally.

The achievement doesn’t show as unlocked on Steam, Xbox Live or in game.

Hopefully there’s a way to fix it, potentially by resetting the achievements triggers or something on those lines?
But I have no idea how to do it.

Please don’t cross post topics, thanks