PLEASE NOTE: eBay errors are common. If your item is showing "Failed to List" after attempting to list, you can learn more by clicking on the item receiving error to see what eBay is asking from your listing under 'eBay Status'.
This means you have a live listing for this same SKU on eBay already. It could either be listed through JoeLister or listed outside of JoeLister on eBay.
To resolve you will need to delist the duplicate listing directly on eBay and try listing the item again on JoeLister.
If this is a non-variation listing and you wish to keep the sales history - you can try connecting the listing using the CSV upload in your Advanced Settings. More information on connecting pre-existing eBay Listings here: https://support.joelister.com/hc/en-us/articles/115005602687-Importing-Stranded-SKUs-or-pre-existing-eBay-and-Shopify-listings