Canvas node's value doesn't update after changing variable's Default Value

Steps to reproduce:

1. Create a new project
2. Import the attached "MySimpleGraph.cs" into the Project
3. Go to Assets > Create > Graph Toolkit Samples > Simple Graph
4. Open the created graph
5. Click the "+" button to add a new variable and drag it to Canvas
6. Select the variable in Canvas and in Graph Inspector, enable "Allow to set value in graph"
7. Change the default value to anything else in the Inspector or Blackboard
8. Observe no change is visible in the Canvas node
9. Disable and enable enable "Allow to set value in graph" again
10. Observe the Canvas node 

Actual results: After 7th step The Canvas node still shows the old value after the Default Value is changed and only updates after re-toggle

Expected results: The Canvas node shows the updated value as soon as the Default Value is changed

Reproducible with versions: 6000.7.0a3 

Can’t test with versions: 6000.5.5f1, 6000.6.0b5 ("Allow to set value in graph" not available)

Tested on (OS): macOS 26.5

Notes:

• The stale display is not specific to the "Allow to set value in graph" checkbox mechanism. Right-clicking the node and choosing "Convert to Constant" - an entirely unrelated context-menu action - also reveals the correct, current value. This shows any action that forces the node's view to rebuild from the model exposes the correct data