I have some additional info (this laptop is <1wk old, I'm still discovering behaviour). If I boot the laptop with the dock plugged in, boltctl sees the dock and cable as connected but the attached ports and peripherals are not visible - except for the external monitor, which does work. If I un-plug then re-plug the dock, the port discovery messages show in kern.log and all the peripherals/usb-hubs/etc. appear.
I have some additional info (this laptop is <1wk old, I'm still discovering behaviour). If I boot the laptop with the dock plugged in, boltctl sees the dock and cable as connected but the attached ports and peripherals are not visible - except for the external monitor, which does work. If I un-plug then re-plug the dock, the port discovery messages show in kern.log and all the peripherals/ usb-hubs/ etc. appear.