Need help - getting error message when trying to refund buyer

[shaoka-25]

Hello,

I'm trying to refund a buyer but getting an error message,  "A post-transaction case exists on this order, seller refund can’t be triggered."   Saw another thread but without a resolution. The buyer opened and closed a return request on May 6th as a result of a conversation between us.  I offered the buyer to keep item and send a full refund, but I can't due to this error message.  Does anyone know how to get this resolved? 

Thank you

[whattheactualfox]

Im going to take a shot in the dark here and guess that perhaps there was a CC chargeback or a bank dispute.

https://community.ebay.com/t5/Selling/Refund/td-p/31691540

Someone on this forum had the same issue.