Game Mechanics: Insufficient Mana

[Yanomamo]

I have noticed this happening for a while now (at least 3 weeks). When trying to cast a spell with JUST enough mana I often get the message "insufficient mana" even though I, in fact, DO have enough mana.

The spell will then try to cast, stop after the same time it takes to fizze, I will lose a Fizzle's worth of mana and then get the message "your spell has been interrupted."

This only happens when i have "just enough" mana. Aka, if the spell I am trying to cast costs 200 mana, this effect never happens as long as i have at least 210-215 mana when i try to cast.