If you encounter the above "spinning wheel" (and blanked out frame where your webcam image should be), the first thing to check is whether you've enabled the correct privacy settings for your camera. These types of settings exist both in the Windows operating system, and possibly also in any camera utilities or anti-virus software that may be installed on your computer.
To check the settings on the Windows 10 operating system level, go into camera privacy settings, as shown in this photo:
Once on the privacy settings page, scroll down and look for the desktop apps permission, and make sure it's set to "on" and that LockDown Browser shows up, as in this photo:
You should also check similar camera privacy settings in camera utilities or anti-virus software that may be installed on your computer.