When File vault 2 is on and when you restart the machine or shutdown and turn on Mac, ONLY local user appears for login and does not show 'Other' to allow other users to login. We have our customers setup with Active Directory accounts and it does not appear when Mac has restarted. It is fine when user ONLY logs off because the 'Username' & 'Password' appears again.
My understanding is since Filevault 2 is on, it needs a local account to unlock the disk in order for other users to use the Mac. So when the Mac is turned or has restarted it only shows the local accounts listed.
Example:
In the attachment, A customer logged in with their Admin Network account, installed software and required a restart, Mac booted back up and ONLY shows local account with no other option.