From https://groups.google.com/g/tvrename/c/2kptAUkAyrg
I did find that changing the filename naming template changes all the video and nfo filenames properly on the hard drive but fails to rename the thumbnail files which causes TVR to redownload them with the new template naming. Therefore, every TV show on my hard drive has a bunch of duplicated original thumbnail files still under the original name. I had to go through every TV show folder and manually delete those. I think I got everything pretty much re-created now.
From https://groups.google.com/g/tvrename/c/2kptAUkAyrg I did find that changing the filename naming template changes all the video and nfo filenames properly on the hard drive but fails to rename the thumbnail files which causes TVR to redownload them with the new template naming. Therefore, every TV show on my hard drive has a bunch of duplicated original thumbnail files still under the original name. I had to go through every TV show folder and manually delete those. I think I got everything pretty much re-created now.