Devourers don't attack every round with adrenaline. I know the devourer ability was nerfed to not trigger every round but somehow its attack got reduced as well. Thus the bug. An adrenalined devourer with nightfall has 2 attack so it should hit 4 times with adrenaline, regardless of how many quanta it absorbs. Sometimes it does. Sometimes it doesn't, like in the screenshot.
This is before and after my turn. Note his HP. Before is 82. After should be 82-8-12-8+5=59 But its 65 because one of my devourers only hit once and only did 2 damage.