Another Olaf Bug
So, in addition to this whole "Olaf doesnt gain mana in any way" bit...he's literally in Ragnarok, getting stunned by glacial unit procs and slowed by Iceborn procs.
Feels horribly bad to try berserkers right now, literally because the one you rely on from the brunt of your physical damage is so buggy that you'd be better off running berserker VEIGAR instead. >.>