Unable to cast Ice Nova of Frostbolts during Lavianga's Spirit

Thanks for you report, this is intended.

Lavianga's Spirit causes your spells to not cost mana during effect.
Your Frostbolt is socketed in Kitava's Thirst which has a chance to trigger socketed spells when you spend 100 mana, because you're not spending mana during Flask Effect your Frostbolt will not trigger.