I have been using Calibre for 15 years and have never encountered this problem before.
I save 5 ebooks by one author using "Save to disk", "Save only Epub format to disk". The files end up in two folders.
One file has the author's name/folder name wrong.
I have, as far as I know, fixed the metadata and all that. The file is in the correct folher in the library.
(I know I can probably use "save to disk in a single folder" as a workaround, but I fear something is wrong with the file somwhere.)
Any ideas?
J
The highlighted file is the one...
https://imgur.com/a/FuKnm5z