None of the roles show up in the Object Grants tab for Users in the Schema Browser in Toad 10.1. Looking at the same user in Toad 9.7, the roles are present. It seems that the issue is isolated to Users that have grants assigned via a role which is granted to another role which is granted to the user.
To replicate the issue, follow the steps below:
1. I created 2 roles and granted rights to each role.
create role engineers;
create role alisoviejo;
grant engineers to alisoviejo;
grant alisoviejo to user_name;
select on schema.employees to engineers;
2. Open the Schema Browser | User | Object Grants tab for the user granted and notice the ALISOVIEJO role is not present?
3. Open the Object Grants tab in Toad 9.7 for the same user and the role will be there.
Waiting for fix in future release of Toad for Oracle.