'Sign in' button greyed out

I can’t seem to be able to sign from the Unity launcher, the ‘Sign In’ button is greyed out.
I’ve just updated to the latest version (2018.1.1f1), but everything was working fine before.
Internet is working just fine, and I do see the button light up for a very brief second at the beginning before being grayed out.

Any ideas on how to fix it?

This worked for me:

   1.   Close the editor  
   2.   Sign out in Unity Hub
   3.   Sign in within Unity Hub
   4.   Open the project in the editor

Nevermind, I somehow fixed it.

All I had to do was restart the Windows Event Log service straight from the Services panel in Windows.

Facing this on Unity 2020 LTS, Windows 10 64bit

I could not restart Windows Event Log because other programs/services were using it.

Ctrl + Shift + Esc, kill all Unity/Unity Hub running processes, then reopen them. This worked for me.