Has anyone found a solution for this? I am on Linux. When I select "Add Microsoft Account" the launcher freezes. If I kill the launcher process, the browser then opens for the Microsoft login, but fails since I had to kill the launcher to get past the hang.
I found kind of a workaround. After starting the launcher, I selected the Microsoft login to get it to where it freezes. In the terminal, I checked the browser process (ps -aux | grep firefox), and I saw the login.live.com... really long URL. I copied the URL into the browser and it took me to the Microsoft login request page. From there, I accepted the authentication request, and the launcher moved forward.