Is there a way to recreate thumbnails after changing the crob settings? Will deleting the thumbnails restart creation process by loading a page?
Note that there is currently a bug with them not re-creating on MODX 3 (MoreGallery 1.16). I have a fix for that standing by to be released, which is on my to do list for Wednesday.
If you need a fix sooner, drop an email to email@example.com and I’m happy to provide patch instructions.