I think this forum post answers the question, but I wanted to confirm to be sure.
Is it not possible to refund a payment through the dashboard in Sandbox mode?
I ask because we’d like to show folks where the refund buttons will be in production mode, but they don’t appear where we’re expecting them:
Correct - this is a known feature gap in sandbox: you cannot refund via the dashboard in sandbox. I’ll update this to be a feature request, but it has come up several times and we are aware.
Has this feature gap been resolved?
I have this same problem …
Would like this feature, too.
We need this as well. In the meantime, is there a way to manually trigger the refund webhook that would replicate the user clicking the refund button within their account?
With our webhook you can send a refund test event. Any refund regardless of where its refunded via the API, Square app, or in the Seller Dashboard will trigger a refund event. 
OK, thats what we will do. Thanks
