The file "I capolavori del Giallo - AA.VV_.epub" is not a valid EPUB, because its not a valid ZIP file, as others have posted - an EPUB is a rebadged ZIP file.
Calibre will only read the content of files when they're added if: a) you have configured the Add Books auto-convert feature; or b) you use the get metadata from file option. Otherwise it just copies the file.
What is the source of the EPUB files?
BR
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