GroupDocs adds some (invisible but clickable in e.g. Word) frames in the text when converting from HTML to RTF. This leads to incorrect text formatting.
I have converted the same HTML file using an online converter (HTML to RTF | CloudConvert) and there it is working fine with no artifacts are added to the result RTF. I could see the same problem using the online converter from GroupDocs ( Online HTML to RTF converter | Free GroupDocs Apps)
source html and converted rtf files:
files.zip (307.6 KB)