Fixing syncing issues with Facebook E-commerce and ad-manager and Instagram shopping

We are having trouble getting products to appear available for tagging with our business' instagram account. There seems to be a domain issue from when we transferred our e-commerce from Squarespace to Shopify, have tried various fixes with deleting / starting again but cannot locate the route of the problem. Looking for someone with extensive Facebook commerce and Instagram shopping knowledge as well knowledge of how these connect with e-commerce domains.