In my short experience I've successfully trapped when not coming in too hot. In the start I had the same problem, and noticed the VSI was close to 1000f/m at touchdown. The replay showed that it should have trapped the 3rd wire, and at least the 4th, but sort of bounced it. Success-ratio was probably in the 60% yay. Actually on one of those instances I actually made the landing - but got wet on the replay, nice rewrite of history there :)
Lately I've tried to control VSI to 500 and it catches every time - I tend to go around if I'm way high of the ball.
Not sure if this is the reason, but maybe something to try.
Modda