Why is my eBay feed from Shopify not syncing correctly?

After months of working perfectly today our feeds from Shopify stopped. We are selling through shopify and ebay but not getting notification when a product has sold on Ebay so in turn is not syncing our stock, an absolute nightmare

Cant re sync because the message: Sync job running in the background has been stuck for days!

Help!!!

If you are using a default eBay app (https://apps.shopify.com/ebay), try opening the ticket with the app support directly.
Contact page:
https://connectebay.zendesk.com/