fatalPeppol BIS Billing 3.0profileUBLBG-16
An invoice shall contain information on "PAYMENT INSTRUCTIONS" (BG-16).
XRechnung requires a payment instruction group (BG-16); the invoice has none. The German public sector needs to know how to pay you.
Add BG-16 with at least the payment means type code BT-81 (UBL cac:PaymentMeans). For a bank transfer use 58 (SEPA credit transfer) and add the IBAN in BT-84.
UBL — context (/ubl-invoice:Invoice | /ubl-creditnote:CreditNote)[$supplierCountryIsDE and $customerCountryIsDE]
cac:PaymentMeans