I felt I should start another thread as although this is similar the the render mask thread it is specific.
The exact same thing is happening with region renders, making my life rather stressful mid-jobs.
The attached images show the difference. Same brightening issues. It makes no difference whether, in the camera settings themselves, exposure is on or off.
This simply occurs when I have autoexposure and auto white balance both checked and try to region render.
I’d be overjoyed if someone could suggest why this happens, whether it’s user error or otherwise.
Unfortunately I had already done finals with it on and the client of course changed things, so I’m a bit screwed with this one. C’est la guerre 
Thanks for taking the time to assess if possible 
I can send a cutdown of the scene if of use.
