Thunderlord not activating on Grgas

Attached game in question in which this occured. Had the mastery when you pressed tab. Not once in the entire game did i get the debuff for it being on cooldown, however our TF did. Unsure if it went off and just didn't display debuff, but i do not think so. The enemy chogath let me auto him 3 times and nothing happened, this was immediately after spawning after a mid-game death so it's doubtful it just wasn't displaying.

Was an aram. Used Superfan skin