I have an issue at my work right now where excel files generated by some Java libraries used by another team do not open in LibreOffice. To share them with memb

I have an issue at my work right now where excel files generated by some Java libraries used by another team do not open in LibreOffice. To share them with members running linux and LO, someone with a real Excel installation has to open it up, and re-save the file, then it is compatible. I think that's what they mean by external entity? I've also personally had problems with openpyxl in python