Why is the receipt editing functionality different for Amount Only POs?

Hello,

We have tested in the DEMO PUM55 environment and have noticed that when a receipt is created and fully matched to a voucher on an amount only PO, it can then be edited and either increased or decreased in value.

This does not happen for Quantity POs - once the receipt was fully matched it does not appear to be editable.

The issue we are seeing in our PUM52 Prod Environment is:

An amount only receipt was fully matched to a voucher and a month later the user increased the value of the receipt. The receipt was not available to associate against future vouchers but the vouchers were flagging with the RULE_R600 match exception.