Can you share a sample part and drawing where you facing the issue. Also what is your SP and OS??
Seems like it's something I'm doing wrong. Not having any luck with 2011 SP.5.0 or 2012 SP1.0. Using Windows 7 X64.
I can get it to work for a circle, but not a randomly drawing sketch.
Edit: Turned out I had to select a line from the sketch I wanted to crop before I pressed Crop View. My bad.