If you fire random Ezreal Qs and dont hit a target the timer doesn't show in the item. Although it still procs it. Using Windows 7.
Says critical strikes give 3% max mana return. 
bolts can critical strike but do not give the 3% max mana return.
Elsewise1 votesCase number one, possible bug.
Case number two, probably intended. Otherwise, you could regen INSANE amounts of mana in a very short amount of time.
BobaFlautist1 votesEssence Reaver triggers on the crit and Runaans triggers on the crit - you're getting Mana for critting, you just aren't getting more Mana for having an additional crit effect. It's a little like asking why shiv crits don't restore extra Mana per unit hit, it's just a little confusing because they do apply on-hit effects.
Manamune sounds like a bug though.
Paroe1 votesEssence Reaver triggers on the crit and Runaans triggers on the crit - you're getting Mana for critting, you just aren't getting more Mana for having an additional crit effect. It's a little like asking why shiv crits don't restore extra Mana per unit hit, it's just a little confusing because they do apply on-hit effects.
Manamune sounds like a bug though.
Manamune gets stacks on a basic attack AND an ability cast. But the basic attack proc only works if the attack HITS, which is why ezreal Q - a skillshot thats treated as a basic attack - can proc both on hit, but not on cast.
