Admin login doesn't open in load
OS X 10.10.0
FM Pro 13 login window just didn't open in load - as used to option-key to log in different user privileges .
Just keep on login as Guest account - option-key didn't work at all
Deleted FM from App -> restarted - > reinstalled FM13.0.1 version and now working again.
I had a similar issue. Thanks to PhilModJunk for pointing out the potential role of keychain in OS X for this issue. Also you may need to de-activate guest login in Manage-Security- Accounts.
Hope that is helpful,