Hello,
We recommend using the latest version of LibreOffice (https://www.libreoffice.org/). Newer releases improve DOCX support, including SmartArt content.
If the SmartArt in your DOCX is not supported by the latest version of LibreOffice (and you need to include SmartArt content rather than using regular images), the recommended solution is to use the MS Word conversion plugin to convert it.
Regards.