Leaking out of energy is a general error among Taiji learners. It occurs in many places and happens quite often.
This is quite difficult to explain. Let me use an example and imagine the following scenario:.
The gun powder from a bullet is emptied into a little heap on the floor of a large room. A lighted match is applied to it. Poof! It burns up with a flash and some smoke, but not much really happens. If that same (intact) bullet was placed into the chamber of the gun it was made for and fired, it posesses a lot of power for destruction!