Image cache issues

I’m pulling my hair out over this issue and I cannot figure out what WordPress is doing…

I had an image at the following address:
https://www.ravenoak.net/wp-content/uploads/2015/08/full-cover_v3_corrected_flat.jpg

I got a new image and uploaded it to the exact same folder (via SMTP) with the exact file name.

In theory, the 4 paragraph image should be replaced by the 3 paragraph one.
If I go to the URL with WordPress’s adding a ? and a number (ex: ?34013) to the end, I see the new image with the 3 paragraphs.
If I go to the page containing the image, (seen here: https://www.ravenoak.net/joy-to-the-worlds ) I also see the 3 paragraphs.
However, if I go to the URL directly with no ? at the end, I still see the 4 paragraph image.
That should be impossible as I replaced it. I’m assuming it’s in cache, but I have cleared the cache on my site.
I’m not using Jetpack’s Photon plugin (though I am using Jetpack), nor the tiled galleries of Jetpack.

Help??