Fbleu asked me to try to expalin the problem:
case 1:
In cpg1.4.27, users where banned only by editing theire profile to put the users in the banned group.
After upgrade to cpg 1.5.x, the banned users are not visible in the user manager, nor after clocking on the "banning users" buton on the admin menu
case 2:
In cpg 1.4.27, some users where banned by editong theire profile, and some using the "banning users" buton on the admin menu
After upgrade to cpg 1.5.x, all users are displayed in the user manager and the banned users are visible in the banned list