Right now you can't immediately spam Spinning Crane Kick while Storm Earth and Fire is active. The only way I can use SPK is to cast another ability like Jab or RSK in between SPK.
Is this a bug?
I don't think I've ever had this issue. Do you have something odd macro'd into anything you are pressing?
Not encountered this issue.
It's an issue with animations, not the abilities themselves. The abilities are being used, but for some reason the clones don't do the animation sometimes, especially when you spam the ability (such as AoE situations with SCK).
Check the buffs the clones get: you can see they get the SCK buff, even if the animation doesn't play.