Moves not consuming proc buffs

[DaiKaede]

So Ill be on say, my assassin in Darkness spec, ill have the proc for Energize on my buffs bar and ill hit Shock, but sometimes it doesnt use or consume the buff, even though the move inflicted damage and then went on cooldown. I get the same thing on my merc, in arsenal spec Ill have the 5 stacks of tracer lock but about 5% of the time ill hit Rail Shot and the same thing happens, rail shot hits and goes on cooldown, but the stacks of the buff were not consumed. Anyone else having this happen?