Why are some tracks in my iTunes grayed out? Note: There seems to have been quite a few threads on grayed out tracks on iTunes but none of them seem to be relevant with my question/issue.

Context: I have just subscribed to Apple Music about 2 weeks ago for the first time. Still on trial period. 

As shown in the image below, these are the 2 albums I added to my library from Apple Music. The first album, I also download the physical files, whereas the second album I do not download for offline listening.

Track 10 for first album is grayed out for some reason, while track 4 for the second album is grayed out.

Both songs are playable. I have no issues playing them despite being shown in gray. 

What is it indicating?
I finally found a solution to this. If you sort by song you can see a check mark next to most songs but the greyed out ones won't be checked. Just make all songs checked and they work again. Hopefully this helps you and others with a similar problem.