If you have an active Mobile Key on your device, but it is not unlocking the door, please verify that you have access to the room which you are trying to open.
Next, verify that your Bluetooth is turned on.
Finally, double check that the application has access to your phone’s Bluetooth and Location Services.
Some devices will remove permissions if the app isn’t used for a certain period of time. You can do this by going into the phone settings, searching for the application, and checking the active Permissions or by deleting and reinstalling the application, accepting all permissions when prompted.
If you are still having issues, contact the hotel's front desk.