ApplicationLoopback sample: suggested usage of GetMixFormat not working (only on Windows 10?)

[F3-L1x]

As #196 brought up, the ApplicationLoopback sample (./cpp/LoopbackCapture.cpp:95) tells, that:

// The app can also call m_AudioClient->GetMixFormat instead to get the capture format.

But that doesn't work and I get an E_NOTIMPL (HResult 0x80004001).
That happens for m_AudioClient->IsFormatSupported() too.

The README mentions:

Note that this sample requires Windows 10 build 20348 or later.

Is GetMixFormat() (and IsFormatSupported()) only supported on Windows build 20348 (which is, as far as I found out, Windows Server 2022 21H2) and later, and not on Windows 10?
Just for clarification, the sample itself works on my Windows 10 22H2 (build 19045) system.

Thanks for any replies.