Hi Mel1958,
Welcome to Community! Having the ability to send invoices to your customers in QuickBooks Self Employed, is a vital part of getting paid on time. I'd be glad to help!
If you haven't done so already, I recommend logging into your account from a web browser. Once you're logged in, review the customer profile to ensure the email address is accurate with no spaces. In addition, I suggest reviewing your billing and subscription page, to ensure your account is active. If you experience the same result, please reach out to QuickBooks Self-Employed Support, for additional assistance from their end.
Feel free to reach back out with any other questions. We'd be happy to assist!
