MFX_ERR_UNSUPPORTED error on QueryIOSurf call.... (Win10)

We have an existing application that leverages the SDK for H.264 decoding.  After a recent driver update (20.19.15.4444) we started to get MFX_ERR_UNSUPPORTED on our call to QueryIOSurf.  If we run with MFX_IMPL_AUTO, we don't get the error, but also don't get hardware enhanced decode.  If we specify any hardware option, we get this MFX_ERR_UNSUPPORTED.  We are decoding to system memory.  One note of interest, the system in question is running Windows 10 and we don't have any monitors connected to the Intel GPU.  This had not been a problem with earlier driver releases.  If we have any monitor connected to the GPU, things work as they should.  I thought this was no longer required on Windows 10?

Please advise.

Steve