I seem to have narrowed it down to an issue of resolution.
When viewed with certain resolutions, the theme attempts to replace the images with a different version of the same images. But since this image does not exist withim the server, it returns a blank result.
So far, the only solution I have come up with, is to find the filename its looking for and create a version of the images with this filename on the server.
But this seems a bit too “lowfi”, since I have still not found the specific function causing the problem in the first place.