Eximus killed via Feast/Nourish don't progress Nightwave task

[malafight]

Hullo!

While playing as Grendel (Prime), I broke an Eximus's shield and ate it with Feast, and I believe I finished it off with Nourish. I was trying to progress the Kill 30 Eximus Nightwave Task (A recovered one from last week, I believe) and this kill didn't give me credit towards it.

I was on Plato, Lua, in a two-player group, and my Feast was augmented with Gourmand. I don't recall what type of Eximus it was, since I wasn't exactly keeping a look out. I haven't tried to replicate it because I no longer have the task active, but I can try again when tasks roll over or if I recover another one before then.