Steps to reproduce:

1. Set tax settings to commit-when-paid and place a taxable order
2. Pay for the order
3. Check Avalara, order should now be showing as a transaction
4. Add something to the order (happens all the time to us)

At this point, the order is now 'unpaid' because adding to the order created an order balance that must be paid.

Add a payment to the order to pay it off.

This fires the commit-when-paid routine (again) which then calls the Commit() routine in Avalara (again).

The Avalara Commit(Order order) routine will try and create an uncommitted Avalara transaction. This fails with error 'DocType is invalid for the requested transaction."

The error handling sees the transaction failed, and bails out entirely.

This is what I've been trying to tell you guys. You can't just always call Commit() when an order is paid. Because there are plenty of ways for an order to become paid AFTER the order is already created as a transaction in Avalara. And Avalara is going throw back an error every single time.

The Taxes.TaxHelper.CommitTaxWhenOrderPaid(order) routine has to check to see if the order is already in Avalara as a transaction. If not, THEN do the commit because it's brand new. Otherwise you have to make the call to update the existing Avalara transaction.

The only workaround possible is using the Recalculate button. Except that's built to fire in the wrong sequence, so things get messed up a different way.