Niklas -- I had Georege Iwaszek send me several original images that failed, then set up a test script to do all of the steps for preview creation (in case it was the order of steps) and they did not fail here. I was trying to put together a package for Diffraction to duplicate the error because they were unable to see it as well. My simple solution for the next release is to just skip that step! It's just a preview anyway.