storage other wrong since change from iPhoto to Photos

Since I've changed (or really: had to change) from iPhoto to Photos on my mac, my iPad mini shows up in iTunes' storage bar completely wrong. I'm syncing my entire picture library, and iTunes says its over 16.000 photos. However, the iPad shows up as only 7.000 photos, but nearly 13 gig of "other". Now, as far as I can tell all my pictures actually show up on the iPad, so I guess I can live with it. It's just a bit annoying and weird. Also, yes, I have restored the thing. Twice. Any Ideas?