Trouble playing music and syncing with iTunes 12.2.0

I am having difficulties both playing music in my iTunes (12.2.0) library, and syncing the contents of my library with my iPhone 6 (8.4).

In iTunes, all of my music appears in the library, however some of my songs are greyed out (see attached image) and I am unable to play them or even download them from the cloud. The songs I am able to play were either purchased on iTunes or imported from a CD. I tried deleting and re-installing iTunes, but this has not helped the problem.

Another problem with iTunes is the inability for all of my songs to sync on my iPhone. Only those that are not greyed out, as previously mentioned, will sync to my phone. I have tried resetting the iPhone, and this did not solve the problem.

I have attempted other fixes I found on this forum, including deleting all non-music files from the iTunes folder- the only problem is that the greyed out songs don't appear in that folder.

Thank you for any advice you can provide.