The standards a very different between marketplaces
Is it still generating sales on CM? If so then that would also be a reason for rejection as you are an exclusive author
I know I am exclusive author on Envato. When I submit here I wait for the approval but my logo got rejected. Then after rejection I upload this on Creative Market. I did not submit on creative market before Graphic River. As they reject my logo then I go to Creative Market because I have shop approved on creative market as well.