Hello all, I had the same issue and could not figure it out for a while. By trial and error was able to resolve it. Here is what I found. I have one screen connected through usb c directly, another one was connected through a dongle that had hdmi connection and it was not working. The problem for me as I learned was that I had another dongle connected for usb devices, like external hard drive and keyboard. It has an hdmi port, BUT I had nothing connected to it. It still created an issue. As soon as I connected a dongle without any hdmi ports, everything started working properly. Both screens work now. Hopefully this can be helpful to someone else. Posted 4 months ago by  sauser33 This worked for me! I had an extra dongle with an HDMI port and after I disconnected this dongle (and all others), I was able to connect the DVI-D to USB-C dongle to my 24in Cinema Display. For anyone needing to know my systems specs: iMac (24-inch, M1, 2021), Monterey (the devil's OS) 12.5, connecting a 24in Cinema Display connected with a Club USB3.2 Gen1 Type-C to Dual Link DVI-D (HDCP OFF) dongle. Thanks again to sauser33!!!