Not enough mana when I have enoug mana?

I have 500 mana
Level 16 Rolling Slam costs 70 mana, but I am unable to use it because I dont have enough mana
Level 15 Rolling Slam costs 64 mana, I can use this ability
Level 14 Stampede costs 40 mana, I cannot use this ability

I tried Blood Magic, it still says I dont have enough mana.

What am I missing?

Made a fresh lvl 16 Rolling Slam, has the same mana cost, but this one is usable.
Looks like the gem itself broke.