Another possibility that is easy to overlook..

Just under the RH Hand Icon in the camera controls is a key, which controls "Animation On/Off".
(NOTE - this is DIFFERENT from Actor->Lock).
If this key is red (well, pinkish) then the cam won't animate. If it is grey (gray for yanks), then it will...
In either case the camera can be moved (if it's not locked), but if Animation is off, then the movement is only applied to frame 1 (and is fixed there for the rest of the animation).

If it's not that, then I have absolutely idea..

Cheers,
Diolma