Big Sur, ZOOM & slides as virtual background

Been working on this problem for a couple of weeks. The latest discovery I have had is that the ZOOM website shows a drop down menu in Keynote prefs that shows a box ticked under the Interaction space that says "Allow Mission Control, Dashboard and others to use the screen".
In the current version of Keynote, that selection doesn't exist. I tried post the screen grabs of both, but apparently we can't post pics on this site.
So, I think this may hint at a solution?

Big Sur, ZOOM & slides as virtual background
 
 
Q