On Wowhead and Hearthhead, but not ZAM? I see that you do indeed have premium. K, standard troubleshooting first. I know you've done some of this, please indulge me. First
; you don't have a Hearthhead.com ID. You'll need to login/register on Hearthhead for the site to know that you're Premium (Yeah, I know, that's redundant, we're not to that one-login-to-rule-them-all phase yet). Sidebar
: The lowering browser security thing is only for Allakhazam.com sites, so that won't help you over there. Second
: Clear your cookies (at least for the sites in question) and your browser cache. Instructions for most browsers: https://kb.iu.edu/d/ahic
or: http://www.wikihow.com/Clear-Your-Browser%27s-Cookies and http://www.wikihow.com/Clear-Your-Browser%27s-Cache Third
: Be sure you're logged in. You do have to log in to all the sites individually still (see the we're-not-there-yet) note above.
Run through that and see if it helps.