Tried changing the longtitle and the folder that didn't work still doesn't work.
It's weird that the same command on unprotected mobi files will work on some and not others. I can't figure it out.
You can do for /R to make that command apply to all subfolders (all my command line command knowledge is thanks to bOB). I have a folder inside the documents folder and that one has various subfolders, so it came in handy for the 100 or so files.
I gotta admit I learned tons thanks to this experiment (and I haven't given up yet now that the bitterness of having to redo my files is gone (almost)). And I do believe we advanced the cause even if we don't succeed
Now I can convert tons of pdb files at once with the for command. I'm still trying to figure out how to take tons of folders and transform them from HTML to PRC when they have opf files. I'll try that folder name recursive command tomorrow. When there's no opf file since some have covers and some not, the folder by folder approach is the only way to go.