When exporting my crops using the Save Crops tool, sometimes the crops are saved as black images. It seems to happen primarily when the cookie cutter boxes overlap the image too far.
Here's the slides that I'm cutting up. As you can see, the top and second-to-last images have bounding boxes that extend off the image, into gray space.
https://i.imgur.com/LX3mxdC.png
When I click "save crops", those slides are saved as black images.
https://i.imgur.com/NL6EVe0.png