iPhone 6 / iOS 8.3, photos mostly classified as "Other" storage?

Hello everyone,

I've noticed something strange on my iPhone 6, which is running iOS 8.3.

My "Other" storage is huge... something like 13 GB.

Now before everyone starts telling me to restore my phone from backup, that I've got corrupted files, etc... I did that already. I restored the firmware and then restored from backup, and I still have 13 GB of "Other" storage, which is nearly the same amount of space used by my Apps.

I also have a lot of photos on my phone. Over 2,000. When I look at my phone info through iTunes, the amount of storage dedicated to my photos seemed quite small... 2 GB. So, I backed up all my photos, and then began deleting them in large batches. Lo and behold, my "Other" storage is now freeing up.

This seems to go against the conventional wisdom of what "Other" storage is used for. Also, I have not upgraded to the new Photos app, nor am I using iCloud Drive.

Has anyone else noticed this behavior?

Thanks in advance!