A post-transaction case exists on this order, seller refund can’t be triggered. issue_refund API cal

[afridigems]

Hi everyone,

I am trying to issue refund an open case via  eBay Post-Order APIVersion 2.7.5

I am using the following API endpoint.

POST https://api.ebay.com/post-order/v2/casemanagement/{caseId}/issue_refund

 I have also implemented the "Digital Signature" necessary for this call.

I am receiving the following error.

 {"errors":[{"errorId":34916,"domain":"API_FULFILLMENT","category":"BUSINESS","message":"A post-transaction case exists on this order, seller refund can’t be triggered."}]}

By searching through different forums they say that there might be some charge back request by the buyer, but this is also not the case with my buyer.

Can anyone suggest any solution.

Thanks