I noted a problem with user profile pop-ups on 1.1.0.beta7 here, and since the same problem exists on How To Geek’s Discourse I’m guessing it will effect most users running 1.1.0.beta7 with a custom header.
Adding height to the header (by way of image or other: on standard header only, not mobile) offsets the user profile pop-ups by the new height amount. In my case the header image is 400px high, so the user profile pop-ups pop up 400px below the user profile, which means it actually appear off-screen on smaller viewports.
I’ve only added the header image to my Discourse after upgrading to 1.1.0.beta7, so I’m not sure if this is a known problem, though I’ve not found any other posts on it. And I hadn’t noticed it on How To Geek’s Discourse instance previously either.
You can see the problem live by clicking any user profile thumbnail at http://discuss.howtogeek.com/.