Build errors - missing spatialaudioclient.h

When I try to build the engine, it fails with a missing include spatialaudioclient.h. Line 32 or so of Engine/Source/ThirdParty/WindowsMixedRealityInterop/Include/MixedRealityInterop.h includes it, but I can’t find it anywhere or in previous releases. Do I need to do something manual to build or draw down something here to get this working?

I’ve tried the latest release, now downloading 4.25.3 specifically to try.