When accepting Hunt: Warmaster missions, I frequently have the dubious joy of getting one-shotted by enemy warmaster carriers. The issue? The difficulty is set on easy right now, the ship I was flying was a Halberd dreadnaught with Halo III shield enhancement, the shields were at 98% (give or take 1 or two) and I didn't get as much as a warning before I got to the game over screen.

It's also not a singular occurence, I actually happens pretty frequently with that mission type. Is this a bug (most likely some warmaster ability being scaled incorrectly)?

No, plain vanilla game here. Unfortunately I can't reliably reproduce the bug either, as saving/reloading in a mission will fail said mission upon reload. It also doesn't happen each and every time, which further complicates nailing the issue down.

Yep, I've seen this too, although not in a regular mission, but rather as part of the 4X layer against a faction. I wound up letting my fleet engage the carrier (and none of them got one-shot).