Welcome to the Community, @Fruser.

I'm here to help you create progress invoicing in QuickBooks Online.

My colleague mentioned that you can click the Create Invoice button. As I have checked, it is now changed into Convert to Invoice. After clicking, wait for a while to see the pop-up dialogue. See the screenshot below for the sample.

Then choose from the option and click Create Invoice.

You can read this article to learn about progress invoices: Set up and send progress invoices in QuickBooks Online.

 I'm also adding this article or future reference in receiving payment: Record payments in QBO.

Let me know if you have questions about managing invoices in QuickBooks Online. I'm always here to help. Have a great day.