Hi all,
When the customer has a payment term, where discount days are ie 10D and due date also is 10D and Dicount Grace Period is set to ie. 10D. the discount is not accepted if payment is after the due date but within the Grace period.
Set up of Payment discount grace days (GL Setup)

Payment terms 10-4%

Customer ledger entrys

Applying

If Due date is changed - dicount will be accepted. I think Grace period should take priority.