As of this post I’m using Apple’s latest iOS 9.2 and STILL after at least 6 years people are having the same problems simply copying all their photo’s to another device be it their PC / Mac / OneDrive or other Cloud based resource.
This has been, and still is a problem, with not only iTunes 22.214.171.124 but other iPhone communication and backup alternatives such as iMazing and Xilisoft’s iPhone Magic Platinum.
I found a major flaw in iMazing – one you really need to be aware of! I was copying photo’s from my iPhone 5S (IOS 9.2) iTunes says I have 1187 photos, my phone says in the Photo app that I have 1,175 photo’s. iMazing says I have only 1,051 photo’s and yet when I select ALL my photo’s and select Export iMazing goes through ‘all the motions’ but when I look in the folder on my PC I only have 361 photos!
This issue as far as I can see has been a problem going ALL the way back. MacRumours have posts that go back to 2010 where people still had this issue:
emjaycee18 says clearing the photo cache worked for him, yet others say they tried this but it did not work for them.
Another person says performing a ‘Factory Reset’ worked for him and setting his phone up as a ‘New Phone’ solved the problem.