There was an error when saving a Sales Receipt QuickBooks Error message you have no items or one or more of your amounts is not associated with an item please enter an item.
This error generally occurs when we don’t have the data updated in Webgility from QuickBooks.
Verify the mapping of the items in the order and ensure that the items are correctly mapped with their corresponding QuickBooks items. Review your existing mappings.
Download the items from QuickBooks from scratch. To do the same, refer to the help article Download Data from Scratch.
Once completed, save all the accounting settings by navigating to Settings> Accounting.
Once all the settings are saved, try posting the order to QuickBooks again.