I'm having the same problem. I can't tell you how many times & how many different versions of QuickPwn i've tried, so it's not like the app is corrupted or anything.
Happened the same to me SO many times (using the latest QuickPwnGUI 1.2.0)
What I did was, when it was stuck at that point, remove the USB cable and plug it back again. It then jumped to "Performing operation 4, -1% done" and the jailbreak process completed successfully.