Reason Code automatically defaulted in dispute created from FBL5N

Hi Guys,

Your help would be greatly appreciated here.

We have a situation where ONLY for document type RV (Billing transfer), the reason code is defaulted to "AA" awaiting audit. This happens when I select a particular customer invoice from FBL5N and create a dispute from there. While creation of dispute, it does not ask me for any reason code entry and is not even there as an input field, but when I save this dispute and view it in the corresponding FI document, the reason code gets populated as AA in additional information tab of financial document.

We want to change this reason code from AA to DI but we dont seem to find where to change this.

I have revisited every possible configuration for dispute management and even checked "Define Default Values" in dispute management and we have not mentioned AA as default value anywhere. But we are not able to find it. Note: This is happening only for document type RV and for other doc types no reason code gets updated.

Is there any configuration which I might have missed?

Regards,

Sweta