Welcome to the Community space. Allow me to provide steps to help you view invoices that your customer has viewed in QuickBooks Online (QBO).

We can view your customer's invoices by going directly to their transaction list to check all the invoices that have been sent to them. Here's how:

1. Login to your QBO account.
2. Go to the Customers & Leads, and select Customers.
3. Click the specific customer.
4. In the Transaction List section, select Invoices from the Type dropdown.
5. Select the Status of the invoice from the dropdown.
6. The invoices will then show up.

However, if you're referring to the invoice status in QBO, you can view the specific invoice and check its activity. The invoice activity will update in QBO once your customer views it. To proceed, you can follow the steps below:

1. Log in to your QBO account.
2. Go to the Sales tab, then select Invoices.
3. Select the specific invoice.
4. Choose the Status of the invoice from the dropdown.
5. Select the specific invoice to check the Invoice Activity.

If the issue persists, let's open a private window to see if it's a browser issue since it won't save historical data. These are the keyboard shortcuts:

• Mozilla Firefox: CTRL + Shift + P
• Microsoft Edge: CTRL + Shift + N
• Google Chrome: CTRL + Shift + N
• Safari: Command + Shift + N

If you can see the invoices for your customers, then it's safe to say that it's being caused by your browser. We can clear your regular browser's cache to refresh.

Furthermore, you may check out this article to learn how to record invoice payments if your customer plans to pay you in the future: Receive invoice payments in QuickBooks Online.

Feel free to comment below on this thread if you require further assistance with your invoices or any QuickBooks-related queries. I'll be more than happy to assist. Take care.