I've been having an issue for a little while now, maybe since firefox upgraded? When I click a link on the site that opens a new window/tab I don't get the page. What I do get is a blank tab with the a small black square in the upper left corner.

It's almost as if that little square is the page because right clicking in the tab gives the usual right click menu, right clicking on the square gives the usual right click menu for web pages (such as view source etc).

Initially I thought my firefox was acting all wonky, but any other site that uses links that open in a new window are opening correctly. If I right click the link and then select "open in new tab" it's fine. It's really made browsing the store and the site a real PITA to be honest because outside the MP there are various areas that open in new tabs. The redundancy of the deals area doing this more than 1x is frustrating in general but now it's more so.

I am using Firefox 56.0 64 bit on Widows 10

hmmmm, never mind. I don't know what happened but after I wrote that I decided to try safe mode, to see if anything was conflicting with the site coding.

In safe mode it worked just fine. So I re-started and was going to remove add-ons one by one until I found it (I only have 3) but lo & behold it's working just fine now without disabling anything. Must have been some glitch, it's been driving me crazy for over a week lol.