QuickBooks Online only allows selling items with order date after the product’s inventory start date. If you sell an item before the inventory start date, QuickBooks will not allow the invoice to be pushed to QBo.
Orders with inventory (QOH) products can't be dated earlier than the Inventory Start Date for the product.
The solution is to update the inventory start date of this Item, in QBO. Or, change the invoice delivery date to be before the item inventory start date.