The current situation is that I can't use the thunderbolt dock's USB hub normally: it almost always fails to connect - with the generic Ubuntu kernel or with the "5.3.0-25-generic #27~lp1766076" kernel suggested in the comment above.
Trying to boot with the lp1766076 kernel (which I'm currently running after the first boot), boot with the thunderbolt connected, xhci fails. I Attached dmesg log of that. ** Attachment added: "lp1766076-boot-dmesg.log" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1856161/+attachment/5314555/+files/lp1766076-boot-dmesg.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1856161 Title: Thunderbolt dock fails to connect USB devices To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1856161/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs