Hello,
If you cannot send whole log files, could you please, after reproducing the issue, send us of the following command (ran as root):
grep -R nxexec /var/log/*
Knowing your PAM configuration would be also very helpful, so if you could share the contents of:
/etc/pam.d/nx
/etc/pam.d/su
/etc/pam.d/system-auth
we would be grateful.