I'm here to help you with creating an invoice, clb_2101.
I've added a screenshot to where you can see the Invoice button. Simply click the + New and select Invoice.
Another way is through the customer's profile. Select Customers from the Sales tab, then click on the customer's name. From the New transaction drop-down, select Invoice.
We can also perform some steps if you still can't create a new invoice. First, log in and record it using an incognito window. Let's also clear the cache on your browser. This is a junk file that the browser saves and it can cause errors in QuickBooks Online. Additionally, please update your browser cause the old version can also be the reason for this unusual behavior.
I've added this article if you need assistance in sending an invoice or customizing your invoice emails. This link will guide you in recording invoice payments in QuickBooks Online.
Please comment below if you need more help with this. I'll be here!