ADE 1.77.7018 - Is not an image file error?

I'm trying to "Add Image" in ADE V1.77.7018 and keep getting this error:

I've tried the supported types BMP, PNG, and JPG and they all generate this error. Any hints on what I might be doing wrong?

I've attached the 3 image files and the corresponding .txt file.

Cheers, Rob.