I'm creating a new theme and have modified the media settings. From the Settings > Media page, all sizes are marked as 0x0 so they will not be produced.
I am creating only 1 custom thumbnail in my functions.php file. In total I should be expecting only 2 images uploaded to Wordpress (the original file and the post-page-thumb)
After uploading an image through the media library (test1.jpg), I see that there is an additional image being created by Wordpress 768x960 when I go in FileZilla.
My functions.php also includes the ability to view custom images when adding media to posts/pages (see above), however, this additional size is not available from the drop down (only the original and thumbnail created).
My assumption was that WordPress internally does this somewhere for images that are as large as the one I upload (1600x2000). I don't have any plugins activated.
I tested two additional images: test2.jpg (at 768x960) and test3.jpg (at 600x750). test2.jpg still created the additional 768x960 image, while test3.jpg didnt.
Does anyone know what can be causing this issue or a way to fix? Is this an issue with WordPress 4.6.1? I've never experienced it before.
New user so can't include more than two links, but all are viewable here: https://i.stack.imgur.com/SQOo6.png  https://i.stack.imgur.com/05ZRm.png  https://i.stack.imgur.com/TiOLA.png  https://i.stack.imgur.com/HJwSU.png  https://i.stack.imgur.com/bZl69.png