The excessivePageText auditor uses the info.magnolia.services.seo.audit.impl.ParagraphLengthAuditor to count words within paragraphs.
When it finds a paragraph with too many words it attempts to display its results using an info.magnolia.services.seo.app.rendering.AuditPropertyRenderer but this renderer is designed to report on the checking of a particular page property. As such, before rendering it checks that the page node contains a given property. When the page does not contain the property "excessiveText" it fails to render any results.
This renderer should be configured to use a different class that is not dependent on a specific node property such as the info.magnolia.services.seo.app.rendering.GeneralAuditRenderer