For over a year I have been using a Macbook Pro (M1 2020) with two identical Dell P2419H monitors and a J5Create JCD543 docking station. Yesterday the HDMI port in the J5Create docking station failed and their support folks couldn’t fix it. So I replaced it with a Belkin USB-C 11-in-1 multiport dock.
My problem is that now the two Dell monitors work, but they’re mirroring each other (displaying identical screens). One has a HDMI cable and one has a DP cable, and they’re both plugged into the Belkin dock.
When I go to System Preferences and Displays to fix the mirroring, it doesn’t “know” I have two displays. Instead, it only shows one of the Dell monitors.
Pressing the Alt button in Displays to go from Night Shift to Detect Monitors doesn’t work. Nothing happens. Neither does the usual round of unplugging/plugging in the monitors and restarting.
I also checked Privacy and Security to make sure that Allow Accessories to Connect is set on Always.
I have the Belkin docking station plugged into one of the Macbook’s USB C ports and the power cord plugged into the other.
I suspect I may need to downgrade from Ventura 13.2.1 as others have reported similar problems, but I haven’t found anyone with my EXACT problem.
(If you’re wondering why I chose the monitor/Macbook combination, I didn’t; they were company issued.)