I just tried it out with this page, and it gets the HN icon for me. I am on Nightly and on Linux, so possibly this is an actual bug you're running into, but no fix in sight might be too pessimistic. But definitely worth reporting otherewise.
Keep in mind that just because it works for me, that doesn't mean that you're not running into a bug that I'm not, so I can't make any promises about it actually being fixed for you :)
