iTunes not showing songs / Wish List on Mac or anything on 5S

Okay, so here's the deal: lately iTunes has not been cooperating with me, whether it's been on my retina MacBook Pro or my gold iPhone 5S. Here's how it's been acting with each:

• In iTunes on my Mac, when I go to search for a song or artist, the "Songs" list shows nothing at all, just an empty list. It'll show a few of the albums in the search results, but only enough to fill the length of the screen. If, by some rare chance that it does show the songs, nothing can be sorted by artist or name. My Wish List also shows nothing whatsoever, be it songs or apps or whatever.
• On my 5S, whenever I load the iTunes Store application, nothing will show on ANY of the sections. I thought this was an issue that arose with my iPhone 5 back on 6.1, but I lost everything (corrupt iMessage files) and started new (without a backup) and this iTunes nonsense is still arising, so it couldn't be that.

Now... This is what I tried to do to resolve it:

• I have tried the usual rebooting for both my Mac and my 5S.
• I have tried using both iTunes applications without being signed in with my Apple I.D.
• I have tried updating my Mac to 10.8.5 and iTunes to the latest version (11.1.1). I haven't had to update my 5S to 7.0.2 because it came with it right out of the box.

So, what could be the issue here?

Thanks in advance. 🙂