Sennheiser USB headset not recognized

My older Sennheiser USB headset is not recognized in High Sierra 10.13.4. It works fine under my Sierra partition, which I maintain to run my older software. The headset shows in system information, but does not show up as either an input or output device in Sound preferences. What changed between the OS versions? Why does it see the device but not recognize it as an option for input and output?

Sennheiser USB Headset:

Product ID: 0x3554

Vendor ID: 0x1395

Version: 0.04

Speed: Up to 12 Mb/sec

Manufacturer: Sennheiser Communications

Location ID: 0x14300000 / 4

Current Available (mA): 500

Current Required (mA): 100

Extra Operating Current (mA): 0

Location ID: 0x14300000 / 4

Current Available (mA): 500

Current Required (mA): 100

Extra Operating Current (mA): 0