"glTF-Default-Material" is destroyed when asset settings changes

[anonymous2585]

Describe the bug
A mesh without material is imported with a default material called "glTF-Default-Material".
When changing the animation type, the asset is regenerated but the default material is destroyed, and the mesh become magenta (bright pink).

Files
Cube_no_mat.zip

To Reproduce
Steps to reproduce the behavior:

1. Drag and drop the glb in project asset
2. Drag and drop the model in a scene, see it with default glTF material
3. Select the asset and change "Animation" from "Mecanim" to "Legacy"
4. See the object now magenta in scene

Expected behavior
The object keeps the material "glTF-Default-Material".

Screenshots

Desktop:

• glTFast version: 6.19.0
• Unity Editor version: 6000.3.18f1
• Render Pipeline: BiRP
• Platform: Windows Editor

Additional information:
After deleting the asset from project, at re-import the model is immediately missing the default material, no need to change the animation setting.