https://wattsupwiththat.com/feed/ moved their hosting a couple of weeks ago. It is no longer updating in newsblur, but the live feed (firefox) works, so it looks like the data should be available.
After I posted (of course, after) I experimented with that. When you try to add the site, newsblur seems to replace the URL with the obsolete wordpress one. Still trying to figure that out.
Working now. Sigh. Never mind.