Creating invoices for your customers is the life blood of any business and needed to help track your sales. I'd be happy to help you get your invoices working again.
As QuickBooks Online is a web based program it relies on your web browser to work properly. When a feature isn't working it's usually due to your cache and cookies being damaged or corrupted. To clear out your cache and cookies you can follow the steps in this article. If the issue persists I suggest trying in a private browser such as Google chromes incognito mode or a different internet browser all together.
If you continue to have issues with making an invoice I'd recommend contacting our support team using one of the following options.
Schedule a Callback or Chat: click (?)Help in the upper right > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat. Support is available from Monday to Friday between 9 a.m. and 8 p.m. ET.