Nikolay Sivov (@nsivov) commented about dlls/mf/topology_loader.c:
IMFTopology_GetNodeCount(context->output_topology, &node_count);
- if (FAILED(IMFTopology_GetUINT32(context->input_topology, &MF_TOPOLOGY_DXVA_MODE, (UINT32 *)&dxva_mode)))
dxva_mode = 0;
Have you checked if this attribute applies to d3d11 device manager as well, and not only for d3d9?