Yes. It's a bug somewhere in the UI either on the OS X or Casper side.
I see the same thing here for our conference room machines that are configured for automatic login. I have the config profile set to allow this but the OS X GUI doesn't reflect the change. It does work however. I think i had to move the local managed prefs folder out of the way. Set the automatic login and then reboot.
I also made sure Local Only users may login in checked under the Access options and then (even though its the same payload and typically it shouldn't work) i added a custom com.apple.loginwindow plist in the same config profile with only one setting: com.apple.login.mcx.DisableAutoLoginClient=false
Thanks @tomRGA! It's interesting, if you go to Security & Privacy and enable "Disable automatic login" you get prompted to enter credentials to automatically log in as a user. If you cancel, because that makes no sense, the box doesn't get checked. Very buggy! I'll try the solution you describe.
FWIW make sure that you're not attempting to enable auto-login behavior on a FileVault enabled Mac. This might be obvious to some, but I'll have you know that I spent an hour on this yesterday before I realized that it's futile. Yay, me. [https://support.apple.com/en-us/HT201476](link URL)