[Juan Mortyme]

I'm glad for you everything is working as it should on your system, although you need to duplicate the fanart0, fanart1 etc images in an extrafanart folders. I did so for my tv shows.

I did a test. I've put an image from an different artist in the extrafanart folder. In the Shelf3D view I can see this image immediately in the thumbnail window. However, in the background it never appears. I ran AWB add missing artwork.

I now have 7 different fanart images in the extrafanart folder. In the background I'm seeing images, that I have never stored in the extrafanart folder. I'm pretty sure my local images are being ignored. I noticed this behaviour, because for a lot of artist in my library there's no online fanart available. This used to work fine previously. I only see the default fanart for these less known artists now.

EDIT: I'm experiencing the same issue under Matrix. A lot of live concert images for Queen in the background. I did not download these images to my Artist Information folder.

@MB1968 

Well don't be too happy for me, sure my Leia setup is working but it's not on my home entertainment computer. The H.E. computer which is my daily driver is hooked into surround sound and living room TV, it has Matrix installed and the music artist fanart is not working worth a damn. I tried as best I could to duplicate the skin and add-on setting from Leia but alas no joy.

I too have many local, indie and internet artist that can't be found in any mainstream online database. Hand made the art for those myself.

A Queen fan are you? I was fortunate enough to have seen them twice. First on their Night At The Opera Tour and then again on their New Of The World Tour. I still have the Tour Programs kicking around as well as an original Tour Poster I personally snatched and later got framed.

I'm just going to toss out a few random thoughts. Forgive me if they are regurgitated or thing you thought of already.
After you've checked your Artist Slideshow settings take look to see if it cached art or has it's own db somewhere. I believe the default storage location is the addons userdata\addon_data\ folder.
Same thing as above for Metadata and Artwork module.
Again the same as above for Artwork Beef. Note: I have all AWB settings for downloading all turned off leaving only the "use/import/download local art" settings enabled where applicable.
Do you by chance use an advancessettings.xlm and if so do have commands to import artist fanart1, fanart2, etc.?
Next time you delete the simplecache and tumbnails try also deleting the Textures##.db from userdata\Database\ folder.
This one my sound stupid so don't be insulted but I gotta ask. I assume for your artist art you use the short form of file names? Example: clearlogo.png, keyart.jpg, banner.jpg, etc. not prefixed by the artists name like, artistname-banner.jpg, and so on. Right? (please say, right)

An unrelated question. Is your back cover, spine and discart working, I'm just curious?

These are the version numbers of possibly relevant addons I have installed:
Artist Slideshow 3.3.0
Artwork Beef 0.28.5
Artwork Helper 0.9.1
Embuary Helper 1.5.0
ExtendedInfo Script 5.6.1
Metadata and Artwork module 1.0.42
Skin Helper Service 1.1.31

That's all I can think of at the moment. I feel like there is something more at work here then meets the eye. Something we are overlooking?