Mana gets stuck empty
I have encountered a bug that causes the player to get stuck with 0 mana whilst still displaying that the player is at maximum mana.
I was able to trigger it just by spamming a custom wand built using MMOItems that uses mana per attack. I believe it might be caused in some capacity by logging in or out whilst your mana is less than its maximum, although i'm not sure.
I'm also not sure if this is a bug more with MMOCore being the actual mana being broken or MMOItems being the items not detecting the mana is actually full.
The only way to fix this I have found is with a server restart.