Can you post a screenshot example(s)?
A screenshot with what? The missing Text?
I forgot to say that I place the text in InDesign without Formatting (with "Remove Styles and Formatting from Text and Tables").
Knowing bug. In Russian text "K" symbol is a problem, as example. Not try to find which symbol destroy import. Just save as docx and try to import.
I have the best experiences with LibreOffice – to write the RTF with LibreOffice instead of MS Word. We often had such problems with MS Word, not with LibreOffice.