The last thought that occurred was to run authconfig --test.
Authconfig apparently is the command used by various frontends so I
thought output from it could point to the problem
I wish the output would have made more sense to me - it does not quite indicate which files the answers come from.
$ sudo authconfig --test
caching is enabled
nss_files is always enabled
nss_compat is disabled
nss_db is disabled
nss_hesiod is disabled
hesiod LHS = ""
hesiod RHS = ""
nss_ldap is disabled
LDAP+TLS is disabled
LDAP server = "ldap://SRV1.people.local"
LDAP base DN = "dc=people,dc=local"
nss_nis is disabled
NIS server = ""
NIS domain = ""
nss_nisplus is disabled
nss_winbind is disabled
SMB workgroup = "PEOPLE"
SMB servers = "SRV1.PEOPLE.LOCAL"
SMB security = "ads"
SMB realm = "PEOPLE.LOCAL"
Winbind template shell = "/bin/false"
SMB idmap range = "16777216-33554431"
nss_sss is enabled by default
nss_wins is disabled
nss_mdns4_minimal is disabled
DNS preference over NSS or WINS is disabled
pam_unix is always enabled
shadow passwords are enabled
password hashing algorithm is sha512
pam_krb5 is disabled
krb5 realm = ""
krb5 realm via dns is disabled
krb5 kdc = ""
krb5 kdc via dns is disabled
krb5 admin server = ""
pam_ldap is disabled
LDAP+TLS is disabled
LDAP server = "ldap://SRV1.people.local"
LDAP base DN = "dc=people,dc=local"
LDAP schema = "rfc2307"
pam_pkcs11 is disabled
use only smartcard for login is disabled
smartcard module = "coolkey"
smartcard removal action = "Ignore"
pam_fprintd is disabled
pam_ecryptfs is disabled
pam_winbind is disabled
SMB workgroup = "PEOPLE"
SMB servers = "SRV1.PEOPLE.LOCAL"
SMB security = "ads"
SMB realm = "PEOPLE.LOCAL"
pam_sss is enabled by default
credential caching in SSSD is enabled
SSSD use instead of legacy services if possible is enabled
IPAv2 is disabled
IPAv2 domain was not joined
IPAv2 server = ""
IPAv2 realm = ""
IPAv2 domain = ""
pam_pwquality is enabled (try_first_pass retry=3 authtok_type=)
pam_passwdqc is disabled ()
pam_access is disabled ()
pam_mkhomedir or pam_oddjob_mkhomedir is enabled ()
Always authorize local users is enabled ()
Authenticate system accounts against network services is disabled
$