Sub-Graph's Enum Float entries are not updated on the main Shader Graph

How to reproduce:
1. Create a new HDRP project
2. In the Project window, right-click -> Create -> Shader Graph -> Sub Graph
3. Add the Float variable 
4. In the variable Inspector, change the mode to "Enum" 
5. In the Project window, right-click -> Create -> Shader Graph -> Any Shader Graph
6. Add the Sub Graph to the Shader Graph 
7. On the Sub-Graph, add entries under the float variable
8. Open the float drodown on the main Shader Graph and observe the results

Expected results: Added Enum entries are visible in the main Graph
Actual results: Only "Default" entry is visible

Reproducible with: 6000.5.0b9, 6000.6.0a6
Can't test with: 6000.0.76f1, 6000.3.15f1, 6000.4.8f1 (No such functionality)

Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested

Note: Deleting the "Default" entry doesn't change the main dropdown too