This is actually I tool I've never needed or intended. to use but, when using a mobile device, extremely easy to inadvertently hit when scrolling.
The problem then is that it's not so easy to rectify. Unlike the other commands in the cluster under the image. In fact, I've never been able to rectify it once it's happened and I end up just deleting the image and putting it up again.
I have been trying to persevere with one such case (hard refresh and even cache clears have no effect) and have tried rotating again and leaving it overnight etc. No change.
Would it be possible to add a step in between 'are you sure you want to rotate the image?'
There are tons of things like that to rethink or refine when it comes to the mobile display. UMD has so many little links and options everywhere that it's taking a long time to revisit the workflow of all of them for mobile. I will likely end up removing those links, and let you just rotate them when you are on the pic edit form.
After you rotate a pic, your browser will likely still show the cached version of the old pic, requiring a hard-refresh of your browser. Or if your ISP is doing some weird caching itself, that may not even work, but that's rare. If you see images not rotating, try using mobile with wifi turned off, which will reveal whether it's your ISP or not.
I don't know when I'll get to updating / removing those links, but it will likely happen at some point. I don't think I'll go the route of adding a confirmation screen because that's way slower than just using the mass-change form to do it.