I have a Lenovo T440s laptop which is working great under Windows 8.1 x64. The problem is the fingerprint reader is usually not detected.
If I launch the Lenovo Fingerprint Manager it normally reports that the reader cannot be detected. Once in a blue moon It does detect it o I register my pinky and reboot only to find it does see the reader again.
if I go to Windows -> Settings-> Accounts-> Sign in options I can sometimes Add and Remove fingerprints but usually the options are also disabled as presumably the system cannot see the reader.
I have downloaded and successfully installed the Finger print driver and have also gone into the BIOS to unsure the reader is enabled.