An xref macro should not contain a natural cross reference. A natural cross reference is a reference repeating the section heading including its blanks and capitalization. This should only be used within pointy brackets (<<...>>), not within an xref. To use an xref, use the explicit ID of the section instead.

While natural references work for Asciidoctor as of version 2.0.10, this is an unintended behavior. This behavior might be removed in a future release, see GitHub issue asciidoctor/asciidoctor-intellij-plugin/#546 for details.