Update:
I figured if this was a general problem others would jump in. They didn’t, so I did a bit more investigating and it seems I was a bit hasty.
This happened to me when I tried to access MEW Issue-16 and I gave up at that point. It seems that the problem is limited to that issue … or at least, any other issue that I’ve tried appears to be working OK.
Can someone else try issue-16 and see if they have the same trouble?