For the stretch of the model, set the project z-xis setting to 'regular'. I've updated the notes to include this comment.
In terms of the texture, if you are not using the texture embedded directly into the gltf/glb file (which is now the recommended way after I added this support) and you are using the texture in the image editor, the texture size must be larger than the Project settings sprite sheet size. If you need to continue to use the texture in the image editor, I recommend setting the Project sprite sheet setting to 512 and then resizing any image textures to be larger than 512x512.
In terms of updating the model on the file name change, I have added that to my list of possible future enhancements.