Yeah! I understand your requirements!!! OMG, I could understand jejeje, let's see.
[1] Found no errors in the calibre library database. Then I checked if the files in the library match the info in the database. No error, files match perfectly.
[2 - 4] unfortunately the problem persists exactly with the same books
[5] I select the first one in the list (¡Adiós, Cordera!). From this author, Alas Clarín, Leopoldo, I have 11 books. The other author is Asimov.
From what I have seen, as I have several thousand books, are all the books by the same author, no matter if you have 1 or 100, it is not just some books.
thanks for your assistance, I really appreciate it