I have been using virtual backgrounds without issue since March 2020, but in recent weeks I have sporadic issues with Zoom failing to work with any virtual backgrounds. When I turn on the camera, the feed stays black until a pop-up comes up saying that the virtual background is still loading and asking me to start video anyway or stop. I can not ever get the background to work.  Unplugging and reconnecting the webcam, changing ports on the dock, restarting Zoom don't work. Using the mic on the webcam never suffers any issues and works even when the feed is black while Zoom is apparently attempting to load the virtual background.  Once I click on "Use video" button and ignore the virtual background, the camera works without issue though obviously without the virtual background.

Setup is USB Logitech webcam attached via VAVA USB-C dock on 2019 Macbook Pro running macOS Big Sur 11.4. Zoom version is 5.7.6. 

Has anyone else encountered this or have ideas for fixes or workarounds? 

I am looking to use zoom to have students register for a webinar. I will implement a registration button on my site which when the student clicks it will take them to the Zoom registration page. However, once the student registers, I don't want them to get an email sent out with the meeting invite. I want to suppress that.

I will be implement a "join meeting" button in my platform for the webinar. When the webinar goes live, the students can then click on the join meeting button to join the webinar. How can I do that?

I need my admin assistant to be able to have access to my account to schedule meetings for me. I DO NOT want to pay for her to have a pro account since she is simply supporting me; I have a pro account and she has a basic account. We do pay for a phone for her. How can she access my account besides just giving her my password? She will not be hosting her own meetings. Just setting them for me.  Is my only option to have a pro account for her?  We are a small nonprofit and want to keep costs low.