HI @pixelsmith
I ran into the issue before (more than once)… where WP was creating 1×1 images for all image sizes. I guess… since they are all the same size, they all have the same URL? (I can’t be sure on that though).
At any rate… one time… it was a plugin that was creating 1×1 images for all sizes.. like: add_image_size( ‘thumb-1’, 1, 1, true )
…another time it was image compression software (like WP Smush IT, Shortpixel, Photon) that was messing with image sizes that caused it. I can’t remember the image compression software now (it wasn’t any of the ones listed above tho).
To fix… I removed the tools… regenerated thumbs, and all was good.
So… not sure if it’s an ACF issue… it might have happened within the Media Library during upload by some other hook.
Hope you are able to sort it out, and it’s a simple fix!
