Textures will turn "Black" in AR mode <model-viewer> using KTX 2.0 compression METHOD 3: ETC1S

[andygomez3dart]

Textures will turn "Black" in AR mode using KTX 2.0 compression METHOD 3: ETC1S

In my example I used the following textures:
Diffuse : JPG file, 2048x2048 pixels
Normal: PNG file, 1024x1024
glb size before compression : 10.9 MB
glb size after compression : 2.17 MB

Everything works great and fast in the viewport when using a glb file with the METHOD 3: ETC1S.
The problem comes when I start the AR (augmented reality) mode and the 3D model turns "Black".

I wonder whether there is a problem with the way I applied the textures or it's just an incompatibility between & KTX 2.0 compression at the moment.

Please find attached the screenshots below:

Any idea about what it's going on?

[MarkCallow]

This was answered in issue #409 which is a duplicate of this question.