The web application for "preview" estensions doesn't work correctly


Hello all,
I can’t open my project in the preview extension 5 application. The app start when I press the “preview” button in the Extension builder but when I go to the File->Open menu, the windows keep blanck pointing to the URL:
The same problem when I try to “Connect” to my device. The page keep blank pointing to:
Until yesterday night (at GMT-3) I was using the application but today morning doesn’t work

UPDATE sept 2, 14Hs (GMT-3): Now the preview application doesn’t start. See attach

UPDATE sept 2, 15Hs (GMT-3): SOLVED It works opening in incognito window. I guess it is a cookies problem

I will appreciate your help