Casting time is the number of actions after the current action that are used to cast the spell.  0 Casting Time spells are instant (1 Round only).  1 Casting Time spells use the casting action and one more.  2 Casting Time spells use the casting action and two more.  If it is the case that Blizzard still required three actions, then it would be a bug.  1 Casting Time uses two actions.  Is this what is happening?  Blizzard would normally use up Three Actions, the casting action and 2 turns casting time, so if you have Savant it should take the casting action and 1 turn casting time (total of 2 actions to successfully cast the spell).