Workaround: Team Explorer window is empty
If this is the case...
- Make sure Visual Studio is closed (and devenv.exe not in memory anymore)
- Run: devenv /setup
- Check if it's fixed already. If not, close down VS again.
- Run: devenv /resetuserdata
The Team Explorer window should now look like expected again.
(Thanks to Sven Hubert for the screenshot and workaround verification.)