Someone took a payment for more than what a customer owed. After saving a customer refund for the overpayment, the account field changes back to "undeposited funds" instead of the selected account. Anyone know what the reason could be? The payment itself has been deposited.

The account is tied to the payment method. Set the payment method first then manually overwrite the account

That led me to the issue - The refund method is a check, and the check payment method is set to "group with undeposited funds". Thank you for the info!