Box set album picked up more than 300 images

I decided to split some of my box sets into single albums since they are “Original Jacket Collections”.
For example the Karajan 1980s box: Folder structure is “Karajan 1980s/CD xx”.
Front and back cover scans for each CD are in the respective “CD xx” folders.

That went fine in Roon 1.2: Each CD was identified as CD number xx from the box set and had the correct album cover.

In Roon 1.3, the album art algorithm picked all image files within the Karajan 1980s folder for each album. That means more than 300 images for each of the 78 albums. And even worse, they all have now one and the same cover (the first of the 300 images).

What can I do to get this right?

You may want to add @Joel @support