Karl Bielecke could you double check that the file attached to this issue input.xlsx is the one you're trying to import? If not the case please provide the actual file you're using in your test. For the record I tried again to perform an import of that file in an instance using LibreOffice 25.2.3.2 and still couldn't reproduce. Also can you confirm you manage to just upload the attachment in XWiki to a document?
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