Hello,
LibreOffice 6 and LibreOffice 7 require adding a custom character style to links, to generate active links when transforming the documents to PDF.
Since phpdocx 7.5 you can set a custom character style with addLink (rStyle option inherited from addText method). phpdocx 9.5 added setting a custom character style when transforming HTML to DOCX (on https://www.phpdocx.com/en/forum/default/topic/2012 you can read a sample using phpdocx 9.5 and phpdocx 10).
The next release of phpdocx will automatize adding a custom character style to new links (there's no release date yet).
Regards.