I'm trying to get a T480 ready to give away as a gift. For this, I have purchased a Dell P2419HC monitor with USB-C. My plan was to used the Dell P2419HC as a "docking station", as it is designed to be used as. This works well with Dell laptops. The monitor is connected with a single USB-3 cable to the T480, with power delivery, USB and video running in one single cable.
It's fantastic ... except it doesn't work.

(The USB devices are just a basic Lenovo keyboard and Logitech mouse. And I cannot fully test the USB hub in the monitor, as I don't have any other USB 3 capable devices.)
It's a brand new Windows 10 install with all updates, and all Lenovo drivers loaded via Lenovo's System Update software.
After googling intensely I tried to:
- BIOS update to newest BIOS as of today
- Change all BIOS settings for Thunderbolt 3 to the most permissive -- as I read about similar issues du to Thunderbolt 3 security, and the physical port on the T480 is a dual mode Thunderbolt/USB 3 port.. Settings are now BIOS assist on, and and all Thunderbolt security off.
Any ideas, please?

