Dear All, there is feedback from LibreOffice: https://ask.libreoffice.org/t/is-spreadsheet-corrupt-or-not/113519/4?u=warwound
In summary, they claim the ZIP file was invalid since it contained holes/unused blocks. An additional check for this has been added only recently https://gerrit.libreoffice.org/c/core/+/170571 (which confirms my observation). So do we need to turn to Commons Compress now? Cheers Andreas
