ProBuilder meshes render magenta when the project is imported after the Library is rebuilt

How to reproduce:

1. Create a new URP project
2. Install ProBuilder via Package Manager
3. In the Hierarchy window, right-click and choose Create > ProBuilder > Cube
4. Save Scene with the cube
5. Close the Editor
6. Delete the "Library" folder from the project root folder
7. Reopen the project and open the scene with the cube
8. Observe the Scene view

Actual result: ProBuilder cube renders magenta
Expected result: ProBuilder cube renders with ProBuilder6/Standard Vertex Color and with the same “ProBuilderDefault” material

Reproducible with: 6.1.1 (6000.0.82f1), 6.1.2 (6000.6.0b9, 6000.7.0a5)
Not reproducible with: 6.0.5 (6000.0.0f1), 6.1.0 (6000.0.82f1)

Reproducible on: Windows 11 (25H2)
Not reproducible on: No other environments tested

Workaround: Create any new ProBuilder shape (even another cube) in the same session - this triggers a re-import that rebinds the Shader Graph, and all existing magenta ProBuilder meshes go back to ProBuilder6/Standard Vertex Color (reimporting the ProBuilder package or restarting the Editor not rebinds it)