Not a direct answer to your question, but possibly a resolution to your problem.
Downloading the same image from another source likely resulted in an exact copy (hash-wise) since they probably got it from the same source you did. A wild stab in the dark here, but it’s possible there’s something about the image data or meta-data that doesn’t play nice. What you could try to resolve it is to open the image in your favourite editor and remove or change any meta-data in the image and re-save it. Even if there’s none in there, re-save it anyway (possibly with a different compression setting to force a completely new file). You could even go so far as to save it as a new data-type, such as png.
If that solves it, then you can move on. If it doesn’t I’d say get in touch with the plugin developers and see what they have to say about it.