A site plan will appear on the site plan page of the permit package only if you've defined an installation area by either:
Uploading a 3D XML model
Using the aerial trace-over option
If you've used one of the other installation area definition options instead (i.e. Define Roof Face or Define Ground Area), you can still generate the site plan page, but the actual site plan portion will be blank. When using abstract installation areas, the app has no way of knowing where the installation area is in relation to other equipment or the site itself. As a result, you will then have to manually add a site plan to the page by hand or by using third-party PDF editing software.