VFX Select Unused Properties context menu option selects nodes that are treated as used

Steps to reproduce:

1. Open the attached project
2. Open the New VFX graph asset
3. In the blackboard panel, right-click on the Properties tab
4. Select the 'Select Unused Properties" option 
5. Observe that the New Bool Property is selected
6. Delete the selected Property

Actual results: Confirmation pop-up appears informing about the deletion of a used Property

Expected results: 'Select Unused Properties' option does not select unconnected Properties that are used in the Graph (Current behaviour with Attributes)

Reproducible with versions: 6000.5.0a5, 6000.5.0a8
Can’t test with versions: 6000.0.69f1, 6000.3.10f1, 6000.4.0b11, 6000.5.0a4 (Sorting not available) 

Tested on (OS): Windows 11, macOS 26.3

Notes:

• The issue does not affect Attributes. The project contains an identical setup in which one attribute is added to the graph but remains unconnected. Using the  'Select Unused Custom Attributes' option does not select that Attribute