photo albums in itunes not syncing with iPhone 6

Ever since I purchased my iPhone 6 plus, I have been having sync issues. I noticed that not all selected photos were syncing from iTunes onto my iPhone.

I have tried deleting all and then adding them back, but now none of the albums are syncing.

During the sync process, it gets stuck at the "syncing photos" step. I have tried syncing with my iPhone on and photos open or with it in standby. Does not seem to make a difference. I have read through many threads and can not find any answers to this specific problem.

I am currently running the latest software version. iOS 9.3.4 on my iPhone and OS X Yosemite 10.10.5, iTunes version 12.4.3.1 Photo 1.0.1 on my iMac

Thanks for your help!