It's a bug that's been in since cataclysm hit. It (mainly?) happens when you cast it while the gcd of your other spell is still up. If you wait for the gcd to disappear you won't get the bug (in my expetience).
This is a bug that has been around since Wrath. One way that works 80% of the time, is to jump and cast it, this normally shows the tidal wave animation.
However the spell works fine even when the animation is not visible. Play with it while questing to get a good feel for it.
There is two bugs. The first is with the invisible typhoon that works fine. The second is the typhoon that eats a gcd but never actually casts not consumes the typhoon cool down. This is really annoying in pvp.