I think I have found a bug (undocumented feature ) in the section for Tag to Tag conversion.
When using this procedure to work on _FILENAME, as you build your string in the popup box, MP3Tag creates folders in the destination based on the format string you are creating.
Thank you for reporting and for taking the time to produce the video! I've also reproduced the bug, it happens when the format string contains any folder path that doesn't exist yet.
I've checked the code and the issue is almost 4 years old. It's already present in v3.12 from early 2022, 20 versions back
Not a problem. I think it involves mor than just the ‘workingpath’. I also saw something else funny that I will document here for you. Ill create a new topic for it.