WZFF not getting credit for boss bug

Played Legendary Warzone Firefight on Stormbreak.

Round 4, Banshee Raiders.

Spent a good 3 minutes tackling this one Banshee boss by myself with a Hydra and DMR. I’ve dealt like 90% of the damage, and the boss is nearly dead. My weapons run out, I step inside to resupply, go back out and fire off a DMR magazine into it, but my teammates were also dealing damage at this point. The boss dies and I get zero credit. No assist medal, no score, no REQ energy.

It’s one thing to do almost ALL the damage to a boss and have nothing to show for it, but how did I not get any credit for helping to finish off that last 10% of health?