To be more specific, I could not load the image locally from file into the Destop version of C3, but I could copy and paste the same image from Gimp, where it was exported from, Also the same exported image that was saved locally, loaded fine into other image editors, for example MS paint, also the same image file loaded into the browser version of C3, without problems.
Actually come to think of it now, I think the problem was that the image was saved automatically by Windows to my One Drive, maybe that had something to do with it?