Notebooks in the cloud that do not load / create / open – Mathematica Stack Exchange

I'm not sure if this is the right place to ask, but I can not find a better one for now.

The problem is that when I want to open the wolfram cloud notebook (by clicking on the link "go to the code" in the wolfram alpha responses, or "create a new notebook" here), it does not work. The box appears (the upper bar and the central area are divided into two parts, one for the entry one for the section I forgot what), it flashes and then disappears, leaving the window blank without any input message. The only thing that remains is a blue bar in movement at the top, in the style of modern loading bars that indicate that the program is working without giving an estimate of time.

The problem occurs in Firefox 56 (win7) and 63 (win7 and win10), it does not appear depending on the version.

Please help.