Game Mechanics: Losing Extra Mana When Casting at Full Mana

[turbosilk]

My gnome wizard is losing an extra mana when casting when I'm full mana regardless of the mana cost of the spell. I'm not sure when this issue first started but at least a couple of weeks ago I noticed I was losing a lot of mana on first cast when full or almost full. I've been level 43-45 during this time and am gnome wizard.

When at 207 int, 85 mana from items, 2065 mana pool. If I cast a zero mana instant click item I instantly drop to 1931 mana (134 mana lost). If I regen any amount from 1931 to full mana and insta cast I instantly drop to 1931 mana.

When at 207 int, 85 mana from items, 2065 mana pool. If I cast a 200 mana spell I drop to 1737 mana (328 mana cost/lost on a 200 mana spell).

When at 197 int, 85 mana from items, 2004 mana pool. If I cast a zero mana instant click item I instantly drop to 1931 mana (158 mana lost). If I regen any amount from 1931 to full mana and insta cast I instantly drop to 1931 mana.