Restrict Tool access using DB vault

Dear all ,

I have implemented a rule in oracle DB vault to restrict access to the database based on client role using sys_context in rule expression, however I'm facing an issue: the sys_context with the rule expression always return FALSE for all users. (I simplified the rule expression to be based on user role).

conn dbauser1/*** ( This user has DENY_TOOLS role , the output here is correct)
SQL> select SYS_CONTEXT('SYS_SESSION_ROLES','DENY_TOOLS') from dual;

TRUE

BEGIN
DVSYS.DBMS_MACADM.CREATE_RULE_SET(
rule_set_name => 'Rule_Set_Limit_Tools_Access',
description => 'Rule set to limit access to SQL*Plus',