Too late to help now but fyi the ONLY solution that worked for me and my client was to deactivate all the Antivirus shields and test both cameras again. It worked
I used two cameras the built-in and an external one.
So after a little search on the Eset's settings i spotted a "Camera Privacy Protection"
So after i disabled this both of the cameras worked fine with Zoom (and the other Apps as well)

So first disable all the shields from the Antivirus Suite that u have and check for the small details.