Low-res photos when transferred from iPhone I have an iPhone 4S running iOS 8.1.0

When I take photos using the built-in camera app, and transfer them off my phone using DropBox or PhotoSync the photos mostly end up as low-res versions. Not all of them, but about 90%.

I've spent some time trying to work out what is going on and its melting my brain.

Things I know:


The problem is related somehow to the iPhone camera app as it doesn't happen with Camera+.
The photos do exist on my phone at full-res. If I plug my phone into the laptop with the USB cable, a drive gets mounted and I can get to my photos, copy them off and they are there basking in their high-res glory. That rules out any dumb stuff like 'was I using the front-facing camera' or 'have you set the phone to store photos at low-res'.
If I use DropBox or PhotoSync they come through as (mostly) low-res.
I'm not doing anything with iCloud as I know that causes lower-res versions.


Any help would be appreciated as it is doing my head in!
I believe the problem was fixed in either iOS 8.1.2 or possibly 8.1.1. 

Running iOS 8.1.2, I have tested the same photos from my Camera Roll that gave me the issues described and they now transfer at the correct resolution.