using terminal:
sudo fdesetup add -usertoadd username -usertoadd username -keychain
and or:
- Login as Local Admin
- Add AD User to Filevault(you will need user to input AD Password)- Skip this step if you already added and rebooted and not seeing the AD User.
- Log the Local Admin account out (Do not restart or shut down- just logout).
- Now you should see the AD User(or Users list if multiple had signed in)
- Login as AD USER. Then Log out(do not restart or shur down- just logout).
- from the Login screen now reboot.
- AD Users should now show up as an option to login in.
reference: