Plex won't show artist poster

As the title says, I am having an issue with Plex (version 1.8.4.4249) where it doesn’t show the artist poster when I am looking at my music in a grid view. It only shows a gray square with a small Mic in the middle.

All of my music is carefully tagged and the media library (which is ~400GB) has full write permission in my OS which is Debian 8.

There are no errors that I can see in the error logs.

I checked the Agents under Artists. I am not sure if there’s anything that I need to change in this section.

I have 4 agents under Artists:
Personal Media Artists: Local Media Assets (Artist) then Personal Media Artist
Plex Premium Music: Plex Premium Music then : Local Media Assets (Artist)
Discogs: Discogs then : Local Media Assets (Artist)
Last.fm: Last.fm, Local Media Assets (Artist), Home Theatre Backups then fanart.tv

I just added a single song recently and for some reason it automatically loaded the artist poster for that particular artist. I cannot think of anything different as far as this song goes compared to the rest of my library that would make it identify the artist correctly.

When I choose Refresh All MetaData, it appears that its going through each artists because it shows an orangish circle in the middle of the artist as if its trying to load the artist poster but then doesn’t succeed.

I also forgot to mention that since I have Plex Pass, I thought that I should be able to see lyrics to the songs that I am listening to but it doesn’t show me the lyrics either.