Wrong dropdown content article/products variants/attributes

Dear all,
I am facing a strange problem at an article with its attribute “Color”.
The attribute Color has a lot of color values (e.g. 22 different colors) and the article it self has 4 color variants stored.
When I want to add the article to a proposal, I get all (color) variants stored in the color attribute.
What do I miss. I have other articles where this works fine and just the related colors are shown in the drop down list


Thanks for any idea and help
All the best, Arnold