Asset gets unselected and added Subgraphs list item is not undone when performing Undo in Heatmap with Default Values asset Inspector

Steps to reproduce:

1. Create a new URP 3D project
2. Go to Assets > Create > Shader Graph > Custom Heatmap Values > Heatmap with Default Values
3. Select the asset
4. In the Inspector, expand the "Subgraphs" foldout
5. Click "+" to add a new list item
6. Once added, click Ctrl+Z to undo
7. Observe the behavior

Actual results: The asset gets unselected and undo operation is not performed

Expected results: The newly added list item should be removed when undo is triggered, and the asset should remain selected

Reproducible with versions: 6000.0.0f1, 6000.3.16f1, 6000.4.8f1, 6000.5.0b8, 6000.6.0a5

Tested on (OS): Windows 11

Notes:

• Adding a new list item does not appear in the Undo History
• Does not reproduce with Categories list