This is a bug that I think I noticed before in the beta, but I never mentioned it - I should have! I often work with multiple cameras in a scene, and I've found that you need to be very careful when you create a new camera, because it seems that sometimes if you then move this camera, when you finally place it and run a render, it can copy its coordinates (and rotation and perspective) back to the previous camera you were rendering with, thus losing a POV it might have taken ages to set up. This is what just happened to me - I was fortunate that my files are in Dropbox, so I could recover the earlier version.
I thought that this bug only applied if you duplicated a camera - but in the last instance, I created the new camera in the Cameras tab, and copied coordinates in that I'd taken from the Preview window.
