usermod/useradd with the -G (for supplement groups) does not seem to work

Solaris 11.3 SRU 26  Sparc S7-2.

when I add new groups to /etc/group, either user groupadd or manually with vi,

asmdba::102:oracle

asmadmin::103:oracle

dba::101:oracle

then run # useradd -d /home/oracle -g dba -G asmdba,asmadmin -s /usr/bin/ksh oracle

It returns silently (succeeds).

then when I su - oracle and run id, I only get the primary group returned (dba (101)). is the -G option broken? I would have expected to have it return the supplementary groups as well.

I though this worked in SRU 24, maybe not. Maybe I am remembering different platform.