Hi folks,
I am using the latest version of Vmix, great PC set up etc. I am in a world of hurt when it comes time to stream to Chrome-based services, specifically Streamyard. I can go external no problem to non-browser apps (Zoom, Skype). It has worked in the past but frankly I haven't written down the sequence so it's hit and miss. I choose Vmix External as my camera in Streamyard but it still doesn't work. I have set Vmix Video in Camera settings in Chrome as well.

Any help form the amazing community would be much much appreciated.

The vMix virtual camera should work (it has no sound). If you use external you have to activate external in vMix at the buttom as well. But that is usually used for capture card rendering. Not webcam stuff.
The easiest to work with is NDI tools (free) webcam and enabling NDI on output 1 or whatever is your main output. The NDI signal will have audio and video and will be recognized by -I would say all- tools that use UVC cameras.