For me, it hung up on the upper - Battle Arms Development RACK AR15 Ambidextrous Charging Handle

Let me start by saying that I did end up returning my charging handle.
At first glance this handle is a quality part, with a very clever mechanical design of operation. A little on the bulky side for me, but that is all personal preference.
While pulling from either the left or right side this handle functions very smoothly. Definately comparable and similar to other high end charging handles that I've used.
HOWEVER... If you choose to pull straight back on this charging handle by pulling both levers IT WILL HANG UP ON YOUR UPPER !!
The issue at hand is the fact that when you pull back on a charging handle you are essentially pulling against the resistance of your buffer spring. (I was using a standard mil spec spring). And with this handle. If you choose to pull both sides straight back it requires more pressure to release the handles catch from the upper than it takes to pull back on the buffer spring. Which does result in the charging handles catch hanging up on the notch of your upper.