On Windows 7, the sample rate of an UR816C cannot be set to 176.4kHz or higher.
When being used on Windows 7, some USB host controllers cannot provide the data transfer rate required by USB 3.0.
Switch to High-Speed (USB 2.0) mode in the Yamaha Steinberg USB Driver control panel. This will not affect the functionality of the UR816C. Performance values such as latency will not change.
Alternatively, use your UR816C with a Windows 10 system.