Really strange shadow lords bug (Arbiter/Mira interaction)

I was playing Arbiter against a Mira and Mira took my first health bar. However she had a grenade on her and was on her second. After she killed me, the grenade went off and she died. I got up and laughed cause it was weird. However Shadow Lords counted that mission as a loss and my Arbiter died even though I have 50% of my health left over.

Guess the mimic had the last laugh.