I’m not sure if this is right place to ask, but I can’t come up with better one for now.

Issue is, when I want to open wolfram cloud notebook (clicking “go to code” link in wolfram alpha answers, or “create new Notebook” here), it doesn’t work. Frame (top bar and central area split into two parts, one for input one for I forgot what) appears, flashes and then disappears, leaving window white without any input prompt. Only thing left is a moving blue bar on top, in style of modern loading bars indicating that program is working without giving any time estimate.

Issue happens on Firefox 56 (win7) and 63(win7 and win10), does not appear version dependant.

Help please.