After the new update to the Edge DEV channel, Version 81.0.381.0 (Official build) dev (64-bit), I wanted to test the syncing feature that was added. I had a profile logged into my educational Microsoft account, email@example.com. The syncing still was not connecting (grayed out, "Could'n't connect to the sync server."). I signed out of my profile, so I could sign in again, to see if that would start the syncing.
However, I am no longer able to sign in. When I click the "Sign in" button a dark gray window flashes for a second, titled, "Sign In". Then it closes automatically. I tried to use the "Add a profile" button, to add one from scratch. It takes me to a new tab and the window appears with a "Sign in to sync data" button. When I click this button, the same dark gray window, from the settings screen, flashes and then disappears.
I am unable to sign in to my existing profile or add anew one. I was able to do this on the version before this. I am on a Windows 10 PC connected to my work domain. I believe that it is trying to pass through my login information, but it crashes. I may be wrong, but all I know for sure is that I am unable to sign in or add a profile and I need this fixed.