CommentSold has a setting in place that rejects an order if not accepted within a set amount of time (typically a half-hour). When a Sezzle shopper places an order, and it is not accepted within that time frame, the shopper will get an email stating their order was canceled. During this time, no funds have actually been collected from the shopper, and therefore no refund can be issued - we just kept a temporary authorization on their payment method that then gets reversed.
If you'd like this setting changed, please reach out to CommentSold directly, as they're the ones that will be able to make any changes.