I have a late 2018 Macbook Pro with four USB-C ports. I have used an NEC Multisync PA302W monitor with my Macbook Pro for the last year and a half. This monitor is connected via a Displayport to USB-C cable. I've had the monitor for about 4 years, for my photography work. I just updated to Big Sur and now I cannot get the NEC monitor to come on as a mirroring monitor.
After powering up the Macbook Pro and signing in, I close the laptop cover and normally, when I move my mouse around, the expternal monitor comes on, I sign in again, and all functions on the Macbook Pro are available. Have been to System Preferences --> Display and do not find anything there mentioning an external monitor. I have the monitor set (in System Preferences) on Native Display.
I have also tried disconnecting the power cable for the external monitor for a minute, then reconnecting--no help. The external monitor has worked very well with all prior Mac operating systems, but installing Big Sur seemed to cause the problem.
Has anyone else had this problem with Big Sur and worked through it?? If there is not a way to work around this, can I uninstall Big Sur and reinstall the previous operating system? If that is the solution, please tell me how to proceed.