Gigapixel hangs endlessly in redefine & recover modes?

Tried 2 different computers and I’ve yet to get past the stage where I actually get a preview. It always hangs either on the green bar complete, “Rendering image… FInishing up…”, and probably other similar stages but I’ve yet to get any kind of preview. And I’ve let computers sit overnight to process, tried different images, etc.

If it helps, I’m trying out the demo. But, I’d like to see how it works before I buy, so any help is appreciated!!