Why can't Unpaid Reason be added to receipt in Collections?

Summary:

Cannot setup an Unpaid Reason code for receipts in Collections.

Content (please ensure you mask any confidential information):

Hi,

In Collections, we have both receivables transactions and receipts for a customer account.

For transactions (Type: PA Invoice), there is the possibility to select an Unpaid Reason (from the attached list of values).

However, for the receipts (Type: Standard), this is not possible (Unpaid Reason is greyed out). Please see below:

Is there any way to make this field editable for receipts?

Thank you,
Elena

Version (include the version you are using, if applicable):

24B

Code Snippet (add any code snippets that support your topic, if applicable):