When using the link validator in a course with URLs containing fragments to jump students to specific locations in the syllabus (similar to https://community.canvaslms.com/t5/Getting-Started/Introduction/ta-p/1285#up-next-in-lesson-1-accoun...), the link validator reports the link as "Non-existent content referenced in this resource." This error does not occur for Pages.

In the image below, the link in the bottom-right corner is displayed when hovering over the second result. The course ID is the same and I confirmed that there is an element in the syllabus with id="taxreturn".