How to enable device-specific audio device props?

[HEnquist]

I'm testing the simple audio sample, and I'm trying to add a custom property via KSPROPERTY_AUDIO_DEV_SPECIFIC. The documentation says this property should show up in a new Custom tab in the device control panel, see https://learn.microsoft.com/en-us/windows-hardware/drivers/audio/ksproperty-audio-dev-specific#remarks

The sample driver seems to have the needed bits to add some properties, like a handler here:

Windows-driver-samples/audio/simpleaudiosample/Source/Main/basetopo.cpp

Line 391 in 41b5bca

CMiniportTopologySimpleAudioSample::PropertyHandlerDevSpecific(

I can compile and install the sample driver but the Custom tab doesn't show up, so something is missing but I can't figure out what. Can someone point me in the right direction?