RSTP Stream audio not available to Pixel Stream

Re. UE-78273 the latest update to VlcMedia plugin appears to have resolved rtsp video streaming into UE4. I am able to stream this into UE4 via VlcMedia and then out as a Pixel Stream. However the audio is not available to Pixel Stream (audio plays in UE4 fine).

[2021.06.28-10.29.25:485][  0]PixelStreamingWebRTC: Error: ( Unable to access speaker.
[2021.06.28-10.29.25:486][  0]PixelStreamingWebRTC: Error: ( Failed to query stereo playout.
[2021.06.28-10.29.25:486][  0]PixelStreamingWebRTC: Error: ( Failed to set stereo playout mode.


Any workarounds to get rtsp streaming audio inbound to UE4 available to pixel stream outbound?