MacOS recognizes external monitors, but screens are black

[mpond]

OS: Catalina
Product: Dell D6000 Dock

I have a new MacBook Pro, a new Dell D6000 dock, and two new Dell monitors. I have tried both the classic DisplayLlink driver and the beta MacOs DisplayLink app. In both cases, MacOs recognizes the monitors (I can seem them in Display Preferences in Arrangement) but the screen is black. The screens aren't recognizing a video signal at all and go into power-saving mode. I have made sure Screen Recoding permission has full access. With the classic driver I made sure the driver was loaded and active in the System Report. I have updated the dock firmware (had to do that from a Windows computer). I'm not sure what else to do.