Reproduction steps:
1. Create a new project
2. Create any Shader Graph (Create > Shader Graph)
3. Double-click on the newly created Asset to open Shader Graph window
4. Click on the “” button in the Blackboard and select “Category”
5. Click on the “” button in the Blackboard and select any option and drag it into the Category
6. Click on the “Category” text to expand/collapse the foldout and observe

Actual result: Dropdown doesn’t expand/collapse
Expected result: Dropdown expands/collapses

Reproducible with: 6000.0.66f1, 6000.3.6f1, 6000.4.0b6, 6000.5.0a5

Reproduced on: Windows 11, macOS Sequoia 26.2 (M4)