What you were expecting to happen, and what actually happened?
I expected Fenrir to give my hero, who has the Warden Class and selected the Third trait, which makes him count as a beast, a total of 7 attack, but it only gave the hero the initial 3.
What are the steps to make it happen again?
Get Fenrir to the appropriate amount of mana, then target the Hero after casting the spell.
Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!
EDIT: It is my error, that the Perk for making the hero count as a Beast is ONLY for TEAM BONUSES. Sorry, my apologies.