Q: aperture with macbook pro

Yesterday I dragged a high-quality scan ( .jpg 1200 pixels on one side) of a recent painting to Aperture, so that I could file it for use on my art website. The scan appeared as "normal" when I viewed the image as a thumbnail with other paintings in that category (I file by type of painting), but as soon as I clicked on it to enlarge to the mid-size in Aperture, I got a wildly distorted image.  I will try to attach this screenshot image to this email.  My MacBook Pro is a 2012 model, and I know that Aperture is no longer supported by Apple upgrades.  I'm wondering if my latest OS upgrade (I always install the latest OS) is now incompatible with Aperture??  I have been putting off trying to convert all my photos in Aperture to the photos app, because I have them arranged just as I want them!  Anyone else having this problem with Aperture?

Thanks, Katrina