Zoom Recording

I would try spotlighting for starters: https://support.zoom.us/hc/en-us/articles/201362653-Spotlighting-participants-videos

Note you do need to have at least 3 people with video on for spotlighting to be available. 

You may also want to look at your cloud recording settings and make sure you're only recording active speaker and/or active speaker with shared screen, not gallery view.   Someone from Zoom or another community member with more knowledge than me might want to chime in on this part to confirm if that is true, I'm not sure of Spotlight would overwrite your settings or not.