I had a problem where some things weren't syncing in beta 3, but after a quick reboot of my iPhone everything synced perfectly. I'm sure it says to reboot in this case in the dev notes too, might be wrong though. Worth a try
having the same Problem, Folders are shown, but without content.
turned photo-sync on and off, different source, rebooted all devices, no luck.
Seems to be a Problem of the beta 3, it wasn't there in beta 2.
If anyone knows a solution besides going back to beta 2, let me know.