TBC Quartz cast bar disappears prematurely sometimes when receiving a lot of knockback

[SheerAwesomeness]

Best way to test this is to pull a pack of 5+ mobs and try spamming a spell that gets knocked back. Quite often, the cast bar will disappear before the cast actually finishes.

This doesn't occur with Blizzard's default castbar, Dominos Cast bar, eCB etc.