ZCTransparencyLabel disappearance animation not working

[s1ddok]

I'm using ZCTransparencyLabel in my application, but apparently disappearance animation has some kind of bug since it just stops working in the middle of animation, then stuck for a moment and disappear completely.

I wish somebody could look into that.

[s1ddok]

Workaround for that looks like this:

zcLabel.attributedString = zcLabel.attributedString

But honestly it is very bad. Disappear animation should work without string re-assigning.