Mortar creates Shopify orders and returns in Heartland POS. If line items are missing or returns/refunds for Shopify orders fail to complete in Heartland, confirm the Heartland Retail setting: "Restrict returns to parent transaction" is set to NO.

Correctly configured Heartland Retail returns settings.

"Restrict returns to parent transaction" prevents items not on the original invoice/order from being added to an associated ticket. Example: Mortar product "Shopify Refund" cannot be added to tickets until the "Restrict returns to parent transaction" setting is set to NO.