Warlord's Bloodlust Failure to grant Health upon critical strikes

While playing Yauso in a ranked game, the mastery Warlord's Bloodlust failed to grant any hp upon critical strikes. At first I thought it might have meant "crits against champions only" and that it had been changed. But after achieving 100% crit, no hp was given upon champion crit strikes either. Something is wrong with the mastery essential to crit-based build paths. I wish I had images or something to go with this bug report but sadly, I do not. If this is happening to anyone else or if anyone can assist me (even if that entails telling me to look again) that would be fantastic. Thanks for looking over this.