ThinOS 9.x Microsoft Ergonomic 4000 Keyboard Issue in Horizon

I'm unable to get the multimedia keys working on a Microsoft Ergonomic Keyboard 4000 connected to an Optiplex 3000 Thin Client. None of the silver top row of keys work in the VDI desktop. A newer Microsoft Ergonomic keyboard (Model 1878) works fine when I plug it into the same client, and all special keys work as expected on that. Any suggestions to get the older model working?

ThinOS tested: 2211 and 2208

Optiplex 3000 firmware tested: 1.5.3 and 1.3.1

Horizon Agent: 7.13.1

Windows 10 20H2