Worgen Two Forms bug

I noticed that while playing animation for "Human-into-Worgen" shapeshift you are unable to interact with objects (picking herbs in my case) and attack (tried with my Arcane Shots), and it takes a whole second. Looks like that happens only when you manually change form by using "Two Forms" ability and then try to make another action while you are not converted to Worgen model yet.
When you forced to change your form (for example by attacking while in Human form) bug does not appear and you still have access to all your abilities. When you change your form from Worgen into a Human everything is fine also..
I don't think that is intended to work that way, because changing forms is purely cosmetic and doesn't affect Global Cooldown timer. So it should not affect the use of your combat abilities.