I tried 'hibernate' again and got the error about nvidia not unloading. So I tried 'hibernate --force' again, and got exactly the same result as I do in Kubuntu. Everything rolling along to the point I see something about Atomic Copy on the screen, then the LCD goes "no signal" and the system freezes. A hard reset with the power button brings up a fresh boot; not a restore from hibernate.
Try specifiing the module name to be unloaded. You do this in /etc/hibernate/hibernate.conf
see man hibernate.conf and find this section
UnloadModules <module name> [...] Names of modules to unload prior to suspending.
LoadModules auto|<module name> [...] Names of modules to load after resumimg. If auto is specified, the modules that were unloaded previously are loaded.