Manaflowband on Sion bugged

I played yesterday and had the Manaflow Band rune. After my first death (and possible proccing it while dead?) the rune got stuck at +150 mana and I was unable to get any more stacks from it. I ended the game with the +150 Mana and the rune tab also said "Bonus Mana: 150. Mana restored: 0"