No username box on the login screen

That was the problem. My network account did not have permission to unlock the disk. As a local admin, I gave my network user permission to unlock the disk, rebooted, and now I can log in directly to my network account. Good catch!

FileVault is enabled. For "reasons" the laptop was originally set up by me and I set up FileVault using my local user / admin account. The network account stuff was set up later. Definitely something worth looking at more closely. I'm guessing you are thinking the drive needs to be unlocked by a local admin first.

Unfortunately that option is locked out, I'm guessing by some sort of company policy enforcement. Using a local admin account, the radio buttons are greyed out, and the "Name and password" option is the one selected.

I should have mentioned: in my "Login Options", "Name and password" is selected under "Display login window as".