In version 0.9.8 one page per file does not work. I removed it and downloaded 0.9.7 and it works correctly.
Another user commented on the same thing and was told JPG doesn't support multiple pages and of course I think he new that. I use the JPG format with one page per file checked so that it makes seperate pages but compresses them.
A single file is made and the %d character is at the end of the file in 0.9.8 while in 0.9.7 the %d is the page number.
Images still only print multiple pages to a single file. I am using Imageprinter at the moment to save time. It's a lot slower, and no configure options, but at least it does it in one print.