Kde lock screen and SDDM with pam_fprintd_grosshack.so

I tried using pam_fprintd_grosshack.so with SDDM and the Kde lock screen but it only asked me for a password not both a password and a fingerprint. Can anyone tell me why it didn’t work?

For kde lock screen, you can directly use fingerprint; for SDDM, you need to type ‘enter’ first, then put your finger on the scanner.