I've installed the recommended driver version 418
nvidia-driver-418 using the Ubuntu Software & Updates GUI.
My secure boot is disabled.
$ prime-select query returns only
$ nvidia-smi NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running.
$ sudo prime-select nvidia Info: the nvidia profile is already set
I have rebooted several times, just in-case.
Any help with where to look next would be appreciated.