LibreOffice Writer hangs when trying to load a HTML file which contains an embedded image (e.g. <img src="data:image/png;base64,<base64guff>)
LibreOffice Writer embeds images in this form when one saves a document as HTML, so Writer cannot load HTML files it itself created.
This appears to be reproducible on Windows as well.
*** This bug has been marked as a duplicate of bug 50763 ***