The Surface Pro 4 has an IR camera that lets you login to Windows using Windows Hello Face authentication. The Tobii Eye Tracker also has a Face authentication feature for Windows Hello and when you have a Tobii Eye Tracker mounted to the Surface Pro 4 or an external monitor the Surface will always prioritize the Surface Pro 4 IR camera before the IR camera on the Tobii Eye Tracker.
If you're using an external monitor with the Tobii Eye Tracker mounted and want to login to Windows with Windows Hello, your Surface will detect your face with the integrated IR camera. Currently the workaround for this is to disable the integrated IR camera when you want to use the Tobii Eye Tracker to sign in. Just don't forget to enable it again when you want to use the integrated IR camera on the Surface.
PTP (Precision Touch Pad)
There is unfortunately a driver conflict with our PTP driver. Our PTP driver can't replace the Microsoft PTP Filter Driver, so our driver ends up not being used. The only solution to this is uninstalling the Microsoft PTP Filter Driver, which is not recommended.