I am having the same issue. I have a 16" 2019 MacBook Pro with a AMD Radeon Pro 5500M 8 GB. Clearly, the card is enough to drive two monitors, a 27" LG UltraFine Display and a 27" Apple Thunderbolt Display (with Thunderbolt 2 to 3 Apple adapter). I also use a Logitech G305 mouse, which utilizes one of the Thunderbolt ports. If all three are plugged in and I close the clamshell, only one monitor displays. I then have to open the clamshell, unplug all thunderbolts. Then close the clamshell, plug one device in at a time - sometimes it requires me to restart for things to work. This has been common since I upgraded to Monterey a month ago. Prior to this, all just worked.
dgalliford
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