I've been having some difficulty converting certain mangas, and can't get to the bottom of it. Originally, I'd just try converting as folders and was getting a "Failed to prepare a workspace" error. I checked filename lengths and looked for handles with Process Explorer to no avail. I then decided to try tossing the files into a cbz on the off chance it'd magically fix it. It actually did for one, but I still have 5 others that refuse to convert. When I try doing the conversion as cbz, I get a dialog with a pile of "Cannot create a file when that file already exists" errors. Here's a picture -
Normally I can convert stuff just fine, and I have probably 40 successfully converted files at this point. So it's just a few that won't work.