Welcome to the QuickBooks Community, Dross and Cross. This isn't the type of feelings that I'd wish you to have, and we know how important to process automatic ACH payments from a customer's checking account. I also appreciate the troubleshooting steps you've done to fix the issue about your concern. I'll ensure you'll be able to set up ACH in QuickBooks Online for your customer's payments.

QuickBooks Online has already an option to process an ACH bank transfer for your customer’s sales receipt or invoice. That said, you can now process automatic ACH payments from a customer's checking account. Please know that you'll have to get your customer’s authorization so you can start accepting ACH payments right in your QuickBooks. Then, choose to save their bank info so you don’t have to re-enter it for future use. 

To start with, choose the transaction to receive payment for. You can process a bank transfer payment now for an invoice or sales receipt or add your customer's bank details to a recurring sales receipt.

Here's how for Sales receipt or invoice:

1. Click the + New button.
2. Select Receive Payment or Sales Receipt.
3. Select the customer name from the Customer▼ dropdown menu.
4. Make sure to choose a customer name so you can enter the ACH banking information.
5. Select Check or QuickBooks Payment - Bank from the Payment Method ▼ dropdown menu.

For recurring sales receipts, please follow the steps below. Beforehand, please note that the sales receipt will process the ACH payment on its next scheduled charge date.

1. Click the Gear icon ⚙ and choose Recurring Transactions.
2. Find your customer’s recurring sales receipt from the list and select Edit.
3. From the Payment method▼ dropdown menu, choose Check or QuickBooks Payment - Bank.

Once done, you can now enter your customer’s bank information. Follo these steps:

1. Choose Enter Bank info.
2. Add your customer’s Account Number, Account Type, Routing Number, and Name.
3. Select Use this account information in the future.

After that, you'll get the customer’s authorization before you save the information. Click the signed authorization link to print an authorization paper your customer can fill out and sign. Then, open this article to view additional details and how to complete the process: Process an ACH bank transfer from a customer.

Lastly, you may refer to this article to see various details on how the Sales page provides you with all the status of sales transactions like open and paid invoices: View sales transactions.

Please don't hesitate to post again in QuickBooks Community if you should have questions about ACH payments or anything else. Have a good one, Dross and Cross.