iTunes issue

I'm having an issue with iTunes when it comes to music being greyed out after adding it to my iPhone. The last time I added music to my phone was 2 days ago prior to this;
1. I have made no changes to my iPhone
2. I have made no changes to my iTunes

Now for some reason, when I go to add my music from my library, which plays completely fine, it simply stays greyed out like this:

http://imgur.com/1nlOI7G

Can anyone please help with this? I simply don't understand. Nothing has changed to either device and now it's doing this. I've even tested it with other files, it's doing the same thing now. Not just these files. iTunes does not need updated, my phone does not need updated. This makes no sense.

 

Are you on a Mac? Did you purchase these yourself?

I read a few articles, a few suggest simply logging out of iTunes and logging back in, a couple others suggest deleting and adding it back.

 

Just did some quick research, most come with the same answers as JSand, however another popular answer was go to File --> Library --> Update iCloud Music Library.

Source: https://www.reddit.com/r/apple/comments/3botew/itunes_122_greyed_out_apple_music_songs/