Artist Artwork

Hello

I have tags and artwork embedded in all my music which works perfectly in plex when using personal agent.
I was wondering if theres anyway to automate accumulating artist banners and artwork so that can also be read locally?
I have 800 artists so doing this by hand would be time consuming. Is there anyway to temporarily use either premium or last.fm on the library and repurpose the accumulated info to be stored locally for a personal agent library?
I have tried using a last.fm agent for music and prioritising the personal/local agent above it but for some reason it ignores embedded artwork for a sizeable proportion of my albums.

Thanks in advance for any help.