Reviewing Artwork:

 

 

Important to check:

Artwork is added to Shop for Artwork and then either Original Art or Ltd Edition Original Prints

Then the relevent sub-category based on 'materials used description' - most will be paintings.

You enable the artwork here:

 

 

Very Important the main front image is selected as 'base' and 'main image' and any other is 'thumbnail. If only one image then all can be the same.