@2mellow, The Sandbox environment does not replicate any bank transfer processes, so a pending transfer will not clear or fail automatically after a few business days as it would in production. The transfer will simply remain in the pending state indefinitely.
To process a pending transfer, there’s a “Process bank transfers” button available in the Sandbox Dashboard (https://dashboard-sandbox.dwolla.com), which will process the last 500 bank transfers that occurred on your Sandbox account and Customer accounts you manage (if applicable).
Similar functionality to the button is available in the API by making a POST request to
https://api-sandbox.dwolla.com/sandbox-simulations with an empty request body.