There is a 3rd window that pops (so main scrapebox window, the harvesting window and then when done the stats window pops) - sometimes that stats window gets pushed behind another window. So minimize/maximze or just click a couple times on the scrapebox icon on the start bar usually pushes that window back to the front.
you can try other, like cascade the windows etc.
Also it could be pushed off the screen or on another monitor screen - if you have more then 1 monitor
Assuming it actually finishes.
If its stuck on like 1 final connection thats locked threads and entirely different.