Did you change it while the server was running? If so during stop the
server will probably overwrite the file. Try to change it after stopping
the server:
In fact modifying the file is not good practice, you may prefer to do it
using LDAP:
I have just tested this in my local environment and with minssf=1 it
works correctly, including the ability to search for users in the LDAP
directory from the administration GUI and using those users to log in to
both the administration GUI and to the user portal.