To get the answers on 'what you’re trying to achieve, what steps you take, what happens, and what you think should happen instead.': Please follow the thread on the Ubuntu Forum where not only I report these issues in detail, but also many others. One can not claim that this is 'supported'. Also it is not possible to downgrade the doc without using a Microsoft Windows Operating System, which by it's own would make a certification for LInux obsolete. Some get it running partially, but with heavy restrictions, including myself, by downgrading the firware of the doc to an older version and by accepting a lot of other bugs from that old firmware. It turned out, that this thread had large attentions by the community, and there were plenty of other user which reported the same problem. com/t5/ Ubuntu/ Thinkpad- P1-Gen2- amp-Thunderbolt -3-Workstation- Dock-amp- Linux-Ubuntu- Monitor- s-black/ m-p/4575709? page=1 I own such a device and the corresponding doc, and operated it with the mentioned configuration (including the special kernel) there, but it is not working, so I opened a thread on the lenovo forum there:

There is a claim the 'ThinkPad P1 2nd Gen' is working together with the ThinkPad Thunderbolt 3 WorkStation Dock Gen 2, there:

Lenovo gen2 dock firmware