If you don’t have the Invoice Opportunity action, there’s a couple of things to check:

The invoices for an opportunity are listed under the “Invoices” heading on the left-hand side of an opportunity.

You might have marked the opportunity as “Invoiced” when creating the opportunity. 

Check under the Attributes heading on the details pane to see if your opportunity has been marked as invoiced already.

Edit the opportunity toggle the “Invoiced” slider to NO to mark as not invoiced.

If your opportunity is completed, hit Mark as not invoiced under Actions. 

Project invoicing is a way for billing for multiple opportunities at once. When an opportunity is part of a project with project invoicing enabled, the option to invoice individual opportunities within the project is removed.

If an opportunity is part of a project, you’ll see the name of the project at the top-left of the screen under the organization.

Click on the project name to access the project. Check under the Attributes heading on the details pane to see if your project has project invoicing enabled.

Edit the project and toggle the “Project Invoicing” slider to NO to turn off project invoicing. 

We recommend you check out our guide on project invoicing before adjusting this setting, see: Invoice a project