FBX format is quite large - like other formats - HTML/PDF/DOC … there is much room for misinterpretation (not many apps support the FULL FBX spec from what I have seen)
In FBX you could think of cameras like an armature with a single bone, The armature can be moved, as well as the bone. - Sot the camera supports its own transformations on-top of the objects.
in FBX cameras can have their own:
Blender doesn’t support this (for good reason, IMHO its a fairly strange feature) — but applications (or versions of applications) that choose to write cameras this way, wont load in Blender properly.
Applications can write cameras quite differently but still be valid FBX, but all importers should support all different possible combinations of options.
Blender currently reads the camers object transformation but ignores transformation stored on the camera data (not the object).
But cameras are certainly supported, lens angle, shift-x-y.
One of the reasons I didnt get around to supporting this is its not well documented and I couldnt find many files that use this feature to validate for testing.
Even guys using Autodesks official FBX SDK have some trouble to interpret these values correctly.
You can blame Blender for not reading it right or FBX for making something which (arguably) should be straightforward into a complicated, hassle to support.
So! - its a bug/unsupported-feature… but currently theres lots of them: animation, shape keys, vertex groups… list goes on. Full FBX support for every feature is a really big project, any help to improve support would be very appreciated by users Im sure. and Ill maintain and improve when I get some time to.