OK, this is most certainly a bug. I managed to reproduce it.
If reboot a client system either by running 'sudo reboot' on the cli, or via 'reboot this computer' on the Landscape WebUI - the problem does not occur.
If I reboot the system with 'reboot -fn' in a stored script, I see pending computers upon reboot, they re-request the registration.
OK, this is most certainly a bug. I managed to reproduce it.
If reboot a client system either by running 'sudo reboot' on the cli, or via 'reboot this computer' on the Landscape WebUI - the problem does not occur.
If I reboot the system with 'reboot -fn' in a stored script, I see pending computers upon reboot, they re-request the registration.