A Sales Order will always show status “overdue” when no Delivery Note was submitted, even after the Sales Invoice was paid. While that makes sense with goods it is not quite so necessary with services.
Is there a way to unlink the Delivery Note from the workflow, so Sales Orders change to closed after the payment is received?
Those settings are only a validation for the creation of sales order. (Whether a delivery note is required for a SO to be created or not.)
For your use case, you could try to check the update stock in the invoice and see if that solves it. (No time right now to check it out myself, but that should work.)
@kombi try this solutions : open customize form for sales order , there is a field called skip_delivery_note under company , remove the hidden and set it to default 1 .