"I'm a Beast" Onyx Medal NOT Unlocked

[Kanadier]

Me and a full party played Beast Mode tonight and finally completed all 12 Waves on Insane without failing.
We played all difficulties in one session, so I unlocked the Bronze, Silver and Gold "I'm a Beast" medals, but not the Onyx Medal for beating it on Insane. We played it four times and then once again after I did not receive the Onyx Medal, and i still did not get it after beating Beast mode, on Insane, twice .
All four other party members got the medal, and the Savage Theron Guard. So what am I doing wrong? How come I did not receive the Medal?

I'd really appreciate some help, so thank you in-advance.

[M0RTAL W0UND]

my only thought is that you failed and restarted. However, if you didnt, then I have no clue

[Kanadier]

Okay, attempted Beast on Insane again and finally got the Onyx "I'm a Beast" Medal and the Savage Theron Guard.
Still, if anyone can get this problem noticed, that'd be great.