If you have an untracked listing in Listing Mirror for Amazon and you want to start selling that product on Amazon, it is a quick and easy process!
Go to the Edit Listings page for the listing by clicking on the 'cog' located under the Amazon icon.
Click on Convert to tracked to convert the untracked listing into a tracked listing.
That's all there is to it! This will create an FBM offer in your Amazon Seller Central.
Alternatively, creating the SKU in Amazon Seller Central, Listing Mirror will import the listing (it must have QTY and be active) and Listing Mirror will convert the untracked -> tracked! This applies to both FBA and FBM SKUs!
For more information on untracked listings, here is another article on them!