I had a ton of app updates, but noticed that none would downloaded. I noticed I wasn't logged in, so I tried doing that from the Store menu (screenshot below), yet nothing would happen. No standard username/password box displayed.
I'm thinking about either moving up to the closed beta (just because), or doing a clean install altogether, which would probably fix this iTunes issue in addition to the Calendar.app problem I've been having.

I'm thinking about either moving up to the closed beta (just because), or doing a clean install altogether, which would probably fix this iTunes issue in addition to the Calendar.app problem I've been having.