Using the 5.1.2 sdkmanager (under ubuntu 18.04, x64) I installed full image to Xavier, ORIN.
In both installations I had to arrange an SSH connection between the host and the target, not just USB.
I think this is a wrong concept.
In order to do it I had to stop the installation after the Linux image step, boot the target and set the ethernet connection.
Some added detail: When in recovery mode the Jetson is a custom USB device. This is when flash is performed. After flash the Jetson automatically reboots, and first boot account setup should take place. It is true that ssh is then used for optional software. The part which is not obvious is that the USB cable which flash occurs over then looks like a router to the host PC. The host should see this virtual network device and get its IP address assigned based on this (this will be a different interface than that of the wired ethernet). The default Jetson address on the virtual wired ethernet is 192.168.55.1, and the address on the host PC is 192.168.55.100. If this fails, then it is likely because of security on the host PC not allowing this USB network device without setting it up to do so.
If that virtual address works, then the default shown in sdkmanager of 192.168.55.1 is correct. You can also use other networking if you’ve set that up.