I'd be glad to guide you in printing invoices alphabetically in QuickBooks.
Here's how:
Go to the Sales tab on the left pane, then select Invoices.
Click the Filter drop-down arrow, then modify the fields, and click Apply.
Select on the word Customer at the top of each column in your transactions table to arrange the transactions in alphabetical order. Clicking on it again will reverse the order.
Put a checkmark at the box before the transactions that you'll be printing.
Click the Batch Actions drop-down arrow, then choose Print Invoices.
A pop-up window will appear with the preview of the transactions, then you can print it.
I'm having that same issue in QB Desktop. I do my monthly billing in alpha order but am using 2 different invoices. Could that be the reason they aren't printing in alpha order?