What really is helpful in troubleshooting Service Security related issues is what I call the Service Security circle.

Task/SR -> SR Type -> Responsibility -> User -> Resource 
(and from resource -> Task/SR)

This is a check we always do when somebody complains about not being able to see a resource (in an LOV) or a task or whatever

to explain:

1. if you want to assign a taskSR to a resource, that task/SR has to be linked to an SR-type
2. The SR-type has to mapped to a responsibility
3. that responsibility has to be assigned to a user
4. that user has to be assigned to the resource
5. that resource can be assigned to the Task/SR

If one of the 5 steps/mappings/links above is missing, you need to fix that in order for the resource to be assigned to the Task/SR. Or to view that Task/SR.