How do I get a role_id when querying for shifts (v2 API)?

When I query for shifts, I get valid data, such as the "user_id" and a "start" and "end" time.

I can see "department_id" but "role_id" is always "0"!

What am I doing wrong?

In my case, department will be either "restaurant" or "bar", but I want the role for each shift, which would be something like "cook", "hostess", "dishwasher", etc..

Note that when I query for users and wages, I can see roles just fine.