Eventually that's what I did. I grabbed a bunch from the middle to the end. This time it stopped at image 137. Turned on the index so I could see the image numbers and wound up grabbing about a dozen and ran those. The dozen included the one where it keeps stopping. Worked fine, so there doesn't appear to be anything wrong with the image where it kept stopping. Ran the whole bunch again and it appears every image had a 1:1 preview.
So, didn't work in a big bunch, didn't work in a smaller bunch, worked in a bunch of about a dozen?