I checked your account and I can confirm that when you issued a refund to your client, you also withdrew your earnings from Upwork. The withdrawal was processed, but the refund wasn't processed because of the lack of available funds in your account. Once you have enough earnings/balance in your Upwork account, the refund will be processed accrodingly.
I double checked your account and can confirm that you`ve issued a refund on your contract. I would suggest communicating with your client if there was a confusion on your contract.
If you have any additional questions let me know, if private details are involved please reach out to me via PM. Thank you.