This can happen when when your computer is connected to a domain and the domain policy settings (GPOs) have NOT been set as follows:
Computer Configuration \ Administrative Templates \ System \ Logon \ Turn on convenience PIN sign-in – Not Configured
Computer Configuration \ Administrative Templates \ Windows Components \ Windows Hello for Business
Set all options to not configured. And apply the GPO (gpupdate.exe /force or reboot).
Is it still not working? Maybe there’s another GPO active or you have to clean the old (wrong) registry settings.
They’re located at
Delete all the DWORD keys in there locations (not in the subfolders!).
So the options were greyed out because the setting was configured to enable it. Seems a little counter-intuitive to me….