It has happened but here are my instances. I set up my ultimate from a distance that's from the middle bushes to the baron or dragon instance where the enemy sits directly center and I'm in the bushes. If I ultimate all the way back to the bushes on either side behind where my enemy sits the ultimate will only go to like the bushes right past the bushes I was in. In my opinion, it should have to go to at least him, but it just flops like that. In other instances, I'll ultimate and it will fly way past the bushes past the baron or dragon spawn and keep spinning where I can't even find it, and its the same distance. Somewhere in that area dravens ultimate breaks off bad. It's happened numerous times.