How do I confirm my ownership of images?

While creating a guide I have run into this error:

“ User does not own all of the new images”

The images in question came from our own website, and one of which is a combined image, two pictures taken from our website and combined in Word and re-saved. Is there a way to confirm my ownership of these images?

I tried re-uploading the pictures again today (3 days later) and I did not receive an error and it worked fine. I don't know what fixed it other than the old “turn it off and back on again” perhaps solved it.