(currently)
i am having issues with photos. my iPhone will say i have 28 gb free. i have 28 gigs in photos and camera.
but iTunes will say i have 8 gigs in photos and 20 gigs of other and 12 gigs free.
For the photos, I had the same, then I found the phone has a deleted folder for all the one I thought were gone. Check your deleted folder in photos on the phone.