How to use Graph View with Poly Items

I am attempting to use a Graph View for a recursive data structure with Poly items. For example, a Report item can be related to a Report_Source poly item, which can be a Report, Data, Collector or Aggregator, each of which can also contain a Report_Source relationship. 

For every Report_Source in a particular report, the Query that I defined returns 1 populated and 3 empty Report_Source items, which leaves many empty nodes in the Graph. See the image below, opened only 1 level below the report. When I expand all the sources the graph quickly is overwhelmed with empty nodes.

Is there any way to filter our the Report_Source poly items to just show the next level items?

Also you can see that there are many IDs in the nodes that correspond to foreign Item properties. The Tree Grid builder allows you to refer to a related property using something like foreign/@keyed_name, but this doesn't seem to be supported for Graph Views. Is there any way to fix this?

I am using version 12 build 133441.