can't edit texture transformations

As suggested, I repost this as a bug:
Résolu : Sometimes can't transform textures - by design? - Adobe Community - 14921478

When opening a file like my Cub_round_tex in Viewer as glTF, I get the geometry and the texture applied, but there is no ttols to edit transformations of that texture even if you replace the texture by loading another one.

and I can't find any predifined material in the librairy which allows me to load a custom image as texture...

Many Thanks