CentOS - Aug 2017 - Centos7 - Mate : screensaver troubles after Freeipa-config

Hello All, 

these days one of my tasks is connecting some Centos7 laptops to Freeipa, also
running on Centos7.
After doing that, some users report nog being able to unlock their screens. 
Only after reboot are they able to login again. 

I see this em in /var/log/secure: 

Aug 10 13:34:37 **** mate-screensaver-dialog: pam_sss(mate-screensaver:auth):
authentication failure; logname= uid=382900663 euid=382900663 tty=:0.0 ruser=
rhost= user=*****
Aug 10 13:34:37 **** mate-screensaver-dialog: pam_sss(mate-screensaver:auth):
received for user ******: 17 (Fout tijdens het instellen van legitimatiegegevens
van gebruiker)
Aug 10 13:34:37 **** mate-screensaver-dialog: gkr-pam: the password for the
login keyring was invalid.

Out of the 50 people or so I now have connected to Freeipa, I received some 5
reports.
All users are on fully updated Centos7 machines configured with epel-provided
Mate desktop.

I see a lot of these problems when googling this, but none in Centos. 

Help would be very much appreciated. 

Greetings, J.