Hello there, kolb-scott.

It's possible that the Form name option is not selected in the invoice template. Let's check it out by following these steps:

1. Click the Gear icon located in the upper right-hand corner.
2. Under Your Company, click Custom Form Styles.
3. Click the Edit link of the default invoice template.
4. Click the Content tab, and click the header part of the invoice to expand more options.
5. Under Form, check the Form Numbers box.
6. Click Done.

Then, try printing your invoice and check if the invoice number shows up.

Please let me know if you have additional questions or other concerns about QuickBooks. Thanks.