You should create a bug report in the repo for #1 as it is definitely a bug, the texture editor does not handle compressed textures correctly. I don’t know if it will be able to display the texture in the 2D view but it should at least not make it disappear of the mesh.
For #2, it seems to me that it is the same PG than in #1, so it should work? Maybe you should provide a repro for this one.
For #2 it wouldn’t make sense to create a repro since you must upload a .basis file from your computer. The behaviour seems to be the same for every playground. Upload a .basis file and the you get displayed the default texture.
Thanks for your note, we are switching to the .ktx2 file format!
There is no difference in the source code. I was just working on the right side. I was clicking on the material named “dog” and uploaded a .basis file as diffuse texture from my computer. After that the default texture was visible on the object.