SourceTree cannot load the login-window - cannot use SourceTree

After installation, when I have to login to my Atlassian account, the login-windows stays blank and doesn't load anything even after 20 minutes

I have had this issue now multiple times across various versions - this is annoying as hell and brought me multiple times to the edge of stop using sourcetree anymore, because it simply doesn't work when I need it the most.

Attached you find a very useful blank login page of Sourcetree   EDIT: Yeah, there is no attached screenshot because "JIRA could not attach the file as there was a missing token. Please try attaching the file again." Tried 4 times, screw all of this, it's just having problems......