Thanks for the updates! Glad to hear it is working with the provided cable.
Thunderbolt 3 docks are very demanding of the cable being used. If you need a longer cable, you’ll want to ensure it is rated for Thunderbolt 3 at 40Gbps. Standard USB-C cables won’t work correctly with this dock on Mac and will limit the dock’s ability to function correctly.
While this dock can also operate in USB-C mode, it is not ideal, and Mac systems have more limitations in C mode versus a Windows system. The dock in this mode on Mac would have been trying to mirror the first display to the second (as Mac does not support extended displays over C mode) and since the displays are different models, I suspect it was not able to properly mirror the first to the second.
You should be able to find a longer Thunderbolt 3 40Gbps cable if needed, many manufacturers (including Apple) make up to two meters in length. At this time, our longest 40Gbps cable is the 0.8m cable the dock shipped with.
Should you run into further issues or have additional questions, just let me know!
Thanks and best wishes!