if you have a usb-c to display port, give that a try without a dock
usb-c hub -> usb-c display port only work on high end hubs (i have an alogic right in front of me know that works)
If you’re trying to troubleshoot this, he’s saying to try it with just the cable so that you can identify that it’s the doc causing the issue and not your computer/os/monitor/cables. Remove variables and continue.