Ash here from the Shopify team. Thank you for reaching out in the Community Forums!
I'm sorry to hear you're having trouble selling your store through the Exchange Marketplace. I'm happy to help out! In order to sell your business through the Exchange Marketplace, your store must be eligible to be listed, and you must also meet the user requirements. These can all be found in our Help Center here. I suggest reviewing that documentation again to ensure you meet all of the requirements and that your shop is indeed eligible for listing.
If you've confirmed that you meet the user requirements and that your shop is eligible, then could you please provide me with a bit more information on the problem you're facing when trying to list your shop? Are you getting an error message of some sort? What happens when you try to list your shop?