Filter placeholder $STRUCT.<schema>.<field>$ only works for first match

[arjay54]

I am trying to setup a organisation handbook with role descriptions and role assignments.
I created a serial data table with the role assignment, one person can have several roles.

---- struct serial ----
schema: person_role
cols: *
csv: 0

---- struct table ----
schema: role_activity
cols: *, %title%
filteror: role_responsible = $STRUCT.person_role.role_ns$
filteror: role_performing = $STRUCT.person_role.role_ns$
csv: 0

Filtering the role_activity table only works for the first role assigned. Further matches are not considered. Is there any solution?
Please help.