Okay, so on Safari (Mac), if I click the WWT link in the OP's message, it does nothing. If I go to the nova.astrometry.net
status page and click the "view in WWT" link, it *does* work.
and it ends up at this URL. Copy-pasting that URL to another browser tab, or another browser, also still works.
.... and they only differ in "http" vs "https"!
Hmmmm, now I am also finding that posting the https link into Firefox does *not* work, while the http link *does* work.
I would suggest reporting this to the WWT folks. Nothing Astrometry.net can do about *this*!