All the dvds I've tested are running updatemedia on installation, the checkmark in webadmin is not sticking on any of them though.
FYI, it takes about 10hrs for some media to show up when scanning my NAS, I leave it overnight and everything is available in the morning. So leave things overnight in the scan and it should be there in the morning. This is usually only necessary on initial installs with a fresh database.
J.