Working fear mechanic?

Is it just me or has anyone else noticed that when you ult with Hecarim directly over an enemy champ... they don't get feared? I've seen this happen one other time when a friendly Hecarim ulted a Taric and he was not feared or affected in any way (no there were not any anti-CC tools or items used). In my last game I ulted a Riven on 4 different occasions and of all 4 of them... she wasn't feared or affected a single time. So is this a current issue with Hecarim that riot has managed to overlook? (not that riot ever misses anything cough)