I'm having issues accessing the refunds endpoint on my test system. I found some other threads with similar issues, but those seemed to be related to permissions problems on the app. However I've enabled every app permission to try to resolve it (and have then refreshed the oauth access token), but I'm still getting the 401 Unauthorized error.
The charge I'm attempting to refund was created with the /v1/charges endpoint. It is not associated with an order. I'm able to retrieve the charge with the /v1/charges/id endpoint, but I can't refund it using the same ID.
What else should I check? The documentation on Refunding Payments (under eCommerce API tutorials) says that I should be able to refund a charge created with the /v1/charges endpoint. Are there other restrictions I'm not aware of?
An example ID of a charge I'm trying to refund is TJMA6Y86T2P3C. My test app ID is H5B5NTTATVM6E.