The Sensor Diagnostic Tool is used to confirm that the sensors are able to communicate to the Omnicept Runtime.
It is important to check in Windows Mixed Reality Getting Started with Reverb G2 Omnicept Edition that the sensors are turned on, otherwise you will get false failures in the Sensor Diagnostic Tool. Search for "Getting Started with Reverb G2 Omnicept Edition" in Windows Start bar and you can run through this process to confirm your sensors are turned on.
Also, if you see that the Sensor Diagnostics tool says it cannot connect to the Omnicept Runtime - make sure you are running the Omnicept Runtime in Task Manager. You may need to restart your computer.
If your sensors are enabled and Omnicept Runtime is running but Sensor Diagnostics fails, please contact HP Support to determine if your hardware needs to be replaced.
More detail on troubleshooting here.