I created a LibreOffice text doc and saved it as an MSWord .docx Now 2/3 of the content has disappeared - why & where?

I created a LibreOffice text doc and saved it as an MSWord .docx Now 2/3 of the content has disappeared - why & where?

Please edit the question to indicate in greater detail the nature of the document content and which part has disappeared. This should not occur and needs to be reported as a bug. Thanks.

You should always save LibreOffice Writer documents in the native ODT format, which is standard and robust, and use DOCX only to exchange files with MS Office users. DOCX is not a standard format, and is less robust than ODT (there is an independent research from Symantec, a MS partner, which demonstrate with numbers how poor is the DOCX file format in term of security). When you save using DOCX, LibreOffice warns you about the risks of using an inferior file format such as DOCX. The same applies to XLSX and PPTX. Unfortunately, contents are lost, and the culprit is not LibreOffice but the broken DOCX file format.

Robustness isn’t really relevant when you’re talking about format support: OpenDocument Format types are completely supported (retain everything), where the Micro$hits aren’t, not yet anyways, so you need to use the default, fully supported format before saving as another, not fully supported one.