After emailing an invoice to a customer, if I open my copy within my email client, QB shows that my customer has "Viewed this invoice".

Thanks for posting to the Community, @ranee624.

It's possible that your clients already viewed the invoice in their email when you open the copy in your email. Just in case you wanted to confirm this scenario, you can make a sample invoice and send it to your dummy email. Make sure to view the copy from your main email first (go to the Gear icon, check it in Account and Settings>Sales>Messages>Email me a copy at ).

Once done, refresh the QBO page and then view the invoice status under Invoices in the Sales menu.

This way, you'll know if there's something wrong with viewing the status in customers' invoices.

Also, I've checked the query you've created that is related to this post a while ago. You can check my colleague's answer through this link: https://quickbooks.intuit.com/learn-support/en-us/reports-and-accounting/after-emailing-an-invoice-to-a-customer-if-i-open-my-copy-within/01/562831#M73308.

Please feel free to tag me (@Jovychris_A) if you need more assistance. I'm always here to help. Stay safe and healthy!