I've noticed it many times when using rapid fire + reassemble or an ability into Wildfire, making double weaving almost impossible. Ricochet on the other hand for example is much more forgiving.

I don't think it's a big, i think it's part of the animation lock and has been around since MCH release. I used to use Wildfire but find out it never actually started mid-way through my opener, you just have to test what oGCDs work with what without this weird GCD clipping.