@sumudu That could be a problem, although I do see the endpoints in your page source.
<link href="https://boonbutts.withknown.com/webmention/" rel="http://webmention.org/">
And
<link href="https://boonbutts.withknown.com/webmention/" rel="webmention">
Which is the same as mine. So not sure what else you can do. Would help to know which version and how/where it is hosted.
// @c