I wasn't able to get browserstack. I think we've run out of licenses temporarily. I tried it with Crossbrowsertesting. It's another tool. I was able to reproduce it on Windows 10 and IE 11 only. I tried a number of windows and IE combinations, but only that one exhibited the bug.
I see the following in IE11 on Windows 7 when hovering over the "Without image" link at http://reading-web-staging.wmflabs.org/wiki/Special:AllPages:
I updated the staging server at 1:45 PM UTC today.