Unable to view new photos shared with me in a shared album.

I share an album with my boyfriend and it used to work great butI haven't been able to view photos added over the last 5 months. We will compare settings and photos side by side and everything appears in his shared album but I can't see anything from the last 5 months. There are only 800 photos and I know the limit is 5000. We both got new i phone 6s in the last 12 months and have higher versions than iOS 7. What is wrong?