Internal URL is converted to a plain underlined text

Issue Summary

I installed the pathfilter-5.x-1.x-dev on my website and have done a few tests: <a href="internal:node/12">in several ways</a>.

Sadly when I publish my node with this new filter, the URL is replaced by a simple underlined text: <a>in several ways</a> instead of the expected <a href="http://www.example.com/example">in several ways</a>.

Even more bizarrely, if I do a preview on the node, it works, I can see the hyperlink and when I bring cursor over it, I can see that it has transformed the URL correctly to <a href="http://www.example.com/example">in several ways</a>.

Finally, when I go back to edit the node, the text is actually changed to <a>in several ways</a> . I was expecting this module to his things as part of the output and leave the text alone.

Have you seen this before?

Cheers,
Marc.