MacBook Pro won't mirror screen after update via OCLP

Hi all,

I've just updated my mid-2012 MacBook Pro to Monterey and am happy to say all works great...except, my laptop won't mirror to my Apple TV 4K. I just get a blank screen. I am able to stream my iPhone and iPad to the laptop however, and they also stream to Apple TV no problem. Strangely, before when I was using Catalina, the MacBook streamed to my Apple TV fine.

I've installed all the root patches on the laptop and am running the latest software on Apple TV, as well as the latest Monetary security update. Any ideas, folks? Thank you!