Hi @forstmeier,
I have defined similar interfaces and types and I am able to get a list of all nodes with type LabOrg or StorageOrg in the output on querying with an empty filter.
I see that you are using @auth directive along with types. I suspect that the reason for Graphql returning an empty list is due to the querying user not satisfying the auth rule.
For more details regarding the @auth directive: https://dgraph.io/docs/graphql/authorization/directive/