I think what everyone mistakenly does at first is press up/down on the right analog stick and wait to see the first animation before pushing forward on the left analog stick to complete the move, which is what I was doing initially. However, it doesn't work like that. You have to press up on the right analog and forward on the left analog right after each other like a fighting game. You have to input the command basically before you see the move being performed. Oh, and you have to let go of the left analog stick before you begin the move.
I think another mistake common mistake is holding up/down on the right analog stick, which is also what I was doing at first. To do it correctly, you just tap up/down on the right analog stick once before pressing forward on the left analog stick, which you can hold to continue your players run.