(Not a bug) Ice Wraith not stealing mana

Mobile,, Android 8.0.0

Ice Wraith should steal 5 Mana from frozen enemy. It does not.

How often does this happen? When did it begin happening?
Seems to be consistent, but only noticed since the Bounty started and I was playing it today.

Steps to make it happen again
Play in a bounty with Ice Wraith, freeze an enemy, then cast on the frozen enemy (that has Mana).

Drain works fine

Most of the enemies in this bounty event are immune to mana drain


Thanks… Sorry I overlooked that.