In the psa database once a chroot is assigned, then the shell value is kept in the table 'sys_users', but not before selecting it from the pulldown menu and saving it. Other than that, there are no other places in the psa database which would indicate if you can select it or not.
Check your /etc/shells file to see if it lists /usr/local/psa/bin/chrootsh or not
You can try using
/usr/local/psa/admin/bin/chrootmng
Usage:
--create --source=<source> --target=<target> [--safe]
--remove --source=<source> --target=<target>
--create create chrooted environment
--remove remove chrooted environment
--target=VAL the virtual host directory ("all" for all)
--source=VAL directory ot progs&libs patterns
--safe allow linking suid&sgid files