I am getting a “PostDataInvalidException” error when attempting to add a line item to an existing sales invoice with Xero. The sales invoice is creating in Step 5 of the same Zap, and the invoice ID is pulling from that step. I have verified that the sales invoice is created in Xero, but I am still getting an error when attempting to update the sales invoice. I have tried both the Invoice ID and the Invoice Number from Step 5, and get the same error with both.
