The FSS must be the default scheduler on your system to have CPU shares assignment take effect.
Using a combination of the priocntl and dispadmin commands ensures that the FSS becomes the default scheduler immediately and also after reboot.
For more information, see Using Your Assigned Administrative Rights in Securing Users and Processes in Oracle Solaris 11.4.
$ dispadmin -d FSS
This change takes effect on the next reboot. After reboot, every process on the system runs in the FSS scheduling class.
$ priocntl -s -c FSS -i all