JPEWBDEN is knocking on the solution. My iPhone 6+ had similar symptoms. All photos on PC in Albums, would NOT sync to iPhone (using iTunes). It would sync all the Albums (by name), but each album had 0 photos in it? When I went to General -> About, the iPhone said I had 17,109 photos on my phone, even though I had unchecked Sync Photos box in iTunes, which deleted pics & albums from the phone (should’ve said 59 photos, the current count in my camera roll). Another curious symptom, was that I could see the previous successfully sync’d pics in Collections (the timeline view of photos?). So, certainly, some version of photos *is copied to the iPhone, but, not the Album version?
I tied *many things, to successfully sync my 8,793 photos to my phone. Removed & reinstalled iTunes, nope. Deleted all the ‘iTunes Photo Cache’ files, nope. It was when I found 17,109 photos under About, that I came upon my solution.
Settings -> Apple ID -> iCloud, Turn Photos tab ON.
This warned me that ‘All photos on device would be erased’. Yes! That’s what I wanted! Left iCloud Photos tab ON for a few minutes until General -> About said phone contained 59 photos (the current total of my Camera Roll). Went back to iCloud to turn Photos tab back to OFF. Backed-out of Settings to the begin menu.
Never powered down, nor reset *anything. Connected phone to PC, checked box to Sync Photos, chose location where all my albums are, clicked Sync (bottom, right) and my iTunes is now currently on Step 7 of 7, and is currently copying photo 412 of 8793 (and counting).
Thx for your help, JPEWBDEN. iCloud toggle, fixed me. :-)