Visual Effect Subgraph Operator asset does not open when a default empty Visual Effect Graph window is opened

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Install the Visual Effect Graph package (com.unity.visualeffectgraph)
3. Open the Visual Effect Graph window (Window > Visual Effects > Visual Effect Graph)
4. Create a new Visual Effect Subgraph Operator (Assets > Create > Visual Effects > Visual Effect Subgraph Operator)
5. Double click the new Visual Effect Subgraph Operator to open it
6. Observe the Editor

Actual results: The Visual Effect Subgraph Operator does not open, the default empty Visual Effect Graph window remains

Expected results: The Visual Effect Subgraph Operator is opened

Reproducible with versions: 6000.0.66f1, 6000.3.5f1, 6000.4.0b5, 6000.5.0a5

Tested on (OS): MacOS Silicon Tahoe 26.2, Ubuntu 24.04