To reproduce this issue:
1. Create 1:N relationship managed/group/users from managed/group to managed/user
2. Create a custom policy, such as mytest1, that unconditionally reports policy violation
3. Add the custom policy to managed/group/users
4. Add a user to managed/group/users via Admin UI or POST /openidm/managed/group/<uuid>/users?_action=create. Both are successful despite the custom policy. The policy validation is not fired.
5. Add a user via PATCH
The custom policy is fired.