Einhar's Beastrite Modifier loss

I have found if you kill any other monster with the skill that uses Einhar's Beastrite after u have modifiers from a rare, it will overwrite the modifiers and you just lose them, I would think that it would only do that if the monster u killed was rare with modifiers to overwrite the old ones and refresh the timer.
This is especially annoying if you use a strike skill that will hit more than one unit or accidently miss and hit an unintended target.

Is this an actual bug or am I tripping?

Bump, currently if you want to use this support you have to sacrifice one skill slot because you going to use that skill once or twice per map.

Killing boss, or normal mobs remove those buffs.

If it's not bugged, it would be good to have it mentioned in that support description, that killing any enemy removes active buffs