I've had a few problems with this as well lately, wvdave. I'm a bit confused by it too, and I'm pretty adept at photo manipulation and posting. My recent thread about
the wheat/steel cent spill in the Stories/Pics of Finds section is a perfect example. I rotated a few of the pics with a new app on my phone, and a couple of them still displayed wrong when I uploaded them. I fiddled with them a bit with no success, so I went back to the old app I always used with perfect success and uploaded the photos again (I host them on my own site). Still no luck.
As a last ditch effort, I went to my desk top machine and fired up Photoshop. Rotated all the original pics using that software and uploaded them all over again. I checked my forum post on both the desktop and my laptop, and all looked great, so I went to bed (after wasting over an hour total) satisfied that I licked the problem. Woke up the next morning and checked the thread to read responses, and found that the same 2 photos are still wrong when I look at the post using an iPad or my phone, but correct on a PC or laptop!!
At that point I gave up -- and I have no real idea why some of the photos refuse to cooperate