Other web pages are currently working (I tried restarting Scrivener, too). Just that one doesn’t. Might it be the special character in the name (ā)?
From what I understand about Scrivener’s interactioon with web pages, I realize that it’s probably something in the Apple webkit that’s at fault, but I thought I’d check.
More specifically, it seems to be a problem with whatever browser you are using. I just dragged the URL in successfully from Firefox, so perhaps the browser you have is not handling Unicode URLs correctly.