Dear Paul,
I have the exact same issue and I’m using the UR44 + the Lightning to USB 3 Camera Adapter original von Apple.
I also have followed the steps in the same video, but in streaming + recording a video there is no sound.
But I want to thank you very much for this workaround.
I have also raised a ticket in the hope that we can receive help from one of the technical support members.
Kind regards
Jerryl