It’s still an issue in both window types, (normal and private).
Edit: From what I’m seeing, it seems to be a 403 issue with the v4 API. The earlier errors I received when I was able to access the dashboard referenced this, and upon inspecting the “dashboard is unavailable” page, Google Chrome’s console is also reporting page errors relating to the v4 API. If no one else is seeing it, my guess is that it is a regional problem.