The inspector "Open", "Select", and object field don't work on asset subgraph nodes

Steps to reproduce:

1. Download and import the attached "gtk-subgraph-select-button.unitypackage"
2. Open "Parent graph"
3. Select the subgraph node
4. In the graph inspector, try clicking on "Select", "Open", or the object field.

Actual results: None of them work

Expected results: Clicking on "Select" and on the object field reference pings the asset and selects it, and clicking on "Open" and double-clicking on the object field reference opens that graph in a new window

Tested on (OS): MacOS