12.1.3 ARXRWMAI - Unable to update Net Receipt Amount after receipt is saved

In 12.1.3 I am noticing that in the Receipts form (ARXRWMAI), once the receipt is saved, the Net Receipt Amount cannot be updated any more.

Login as Receivables Manager. Navigate to Receipts > Receipts. Enter the Receipt Method, the Receipt Number and Receipt Amount. Save the record.

The Net Receipt Amount field becomes grayed out and the user cannot update it any more.

This was not the case in 11.5.10.2. Even after the receipt was applied to invoices in 11i, the user could return oto the header and update the receipt amount if required.

Please let me know if this is what you see in your 12.1.3 instances as well. Is there any setup to change this behaviour?