Instruments leaks stopping after app starts
I would chose a development profile for all release,debug modes, clean the simulator, clean xcode ,then i would launch instruments
The Leaks instrument seems to close after the app receives lot of memory warnings. Closing all background applications helps.
clean project build folder, close XCode IDE and clean MAC Os caches then it should work. if it's an iOS project you have to delete app from simulator/device before re compile it.