I have been having issues with some obj files exported from Blender, and finally found the issue.
In some cases the texture index is blank in the face elements portion of the obj file. I have tried with 3.1.0, and 3.3.x, and 3.4.x and the same thing, such as ‘f 3//1 41//1 26//1’
note the missing number between slashes.
What is it about my model that is causing this?