Ctrl-C is not trigered

I have C++ app that registers for SIGINT. When I run it in Terminal outside of Qt Creator it works. But if I debug in Qt Creator with "run in terminal checked"
Ctrl-C does not work. My main thread is sleeping in a loop checking other threads and checking if SIGINT was flagged to exit. When ever I press Ctrl-C or kill -2 from other terminal Qt debugger get interrupted in sleep. If I continue signal never get set so I can't test how application exits.