Camera Flash iPad Air & Pro

We use iPADs for medical documentation purposes and we are constantly taking pictures of forms and EKG strips and various other papers for attachment to our records. For some reason some of our iPADs have the ability to turn the flash on and others do not. There is no discernible pattern to this. All the work iPADs are iPAD Pros and are up to date with the latest iOS. My personal iPAD is a brand new iPAD Air 4th Gen, also with updated iOS. It also has no option for flash. On many of them the only options in the camera app are front/rear camera and whether you want video/photo.

We must have flash active on all cameras in order to eliminate shadows from these documents we're attaching to medical records. Does anyone have any ideas on why some have it and some don't? And more importantly, how to get it fixed? A camera with no flash is like a dead rat falling on your wife's head without a scream: it's no fun.