So the issue is not with the volume rocker but, when you're taking pictures in portrait, if you move your phone to landscape it switches to video mode instead of just flipping the picture? Have you tried switching back to Picture, exiting the camera, and trying again (wondering if it 'remembers' which mode you used for both portrait and landscape)?
I've tried all variations. The volume key works perfectly for portrait. I then delete the photo and try the landscape mode for the same photo but it displays as a video when viewing.
That's what's strange about this. The settings do not change when I move the camera to landscape. It doesn't change after the photo is taken. It's weird and joins the other camera problem of the TAKE A PICTURE command Refusing to work in the landscape mode. The camera switches to portrait involuntarily.