Wrong texture sometimes used in material tooltip preview

When generating navigator tooltip images for 3D materials, wrong texture is sometimes used. E.g. In the attached project, when you first mouse over the cylinderMaterial in navigator, the preview tooltip renders the material using the texture defined for the cubeMaterial. The diffuseColor is correct, though, so it is not simply using wrong material. It might not be used as diffuse texture, though, as there is no transparency like in the correct (cubeMaterial) case.

This typically only happens for the first time the preview is rendered after resetting the puppet; if you move the mouse, to generate another image, it is usually correct.