I FINALLY GOT IT TO WORK!!!! Issue: My external Monitor stopped working after upgrading to BIG SUR. Computer Setup: I have a usb-c adapter connected which allows my external monitor , network, and I plugged my power in usb adapter and speaker to connect... Fix that worked for me: I first unplugged adapter unplug power from adapter reconnect adapt WITHOUT (Usb-c )power connected...FINALLY External monitor was found and displayed Then plugged in usb-c Power to adapter Possible Explanation: Some drivers might no be loading via adapters when Power is connected to it. Basically reconnect everything without power and then connect power to adapters... Personal Commentary: I hope this helps someone....I've been fighting with this mess for 2 days now....APPLE needs to get their act together. This was some old WINDOWS OS BS!!....That why I left Windows.... Where is Steve Job...he would have NEVER allowed THIS to happen to mac users....EXTERNAL MONITOR NOT WORKING???

where you able to get this resolved....???

Upgraded to Big Sur connected my external monitor to my 2018 MacBook Pro via HDMI and doesn't recognize my Benq GL2460 Monitor. It doesn’t even register that anything is plugged in...Rebooted,Plugged and unplugged monitor...Still doesnt work. Has anyone figured this out....My workflow is garbage...I cant