It seems to work fine in our test account. Kindly check the available quantity of the item in stock.
When clicking on the Make delivery note system automatically picks up the received quantity for the line item to return.
if you have create purchase receipt with 1 item example: apple. qty 10 – save submit
and you want to make purchase receipt return example: appel qty 2 --save submit. you can make that.
and you want to make again purchase receipt return example: apple qty 9 , you can not make that, because you create purchase receipt for apple qty 10.
(buy 10 - return 2 - return 9 = -1)