Sales Order => why still status "overdue" after Invoice created and payment received?

[kombi]

Just for my understanding:

A sales order was completed, an invoice created and payment received in full. Still that sales order shows “overdue”.

Why might that be?

[bahaou]

@kombi probably it’s not delivered

[kombi]

very fair point bahaou!

Yet in this example, delivery date is in the past and two delivery notes were sent:

Or can one otherwise mark a sales order as delivered?

[kombi]

sorry, I stand corrected! Those delivery notes were never submitted, that is why!

How does one do it with services though? (stuff that no delivery notes are ever written for)