We have had several users report that some items in Keynote Legends could not be tracked down in any sheet view, even after verifying that keynoting default settings are correct. This issue had me scratching my head for a while until I figured out what was going on.
Here’s a typical scenario where this could occur: You have a core & shell project that was documented and under construction and the model gets copied as a new project for the Tenant build-out phase. As the model cleanup process commences, users start reporting that they cannot find some keynotes that are being reported on the legend.
While troubleshooting, I noticed that when enabling the view's underlay, the phantom keynotes showed up together with the tagged elements, which then led me to tweak the view range and ultimately discover how these project files were started and what the root of the problem was: when the view range was adjusted, keynoted elements were no longer visible, but still reported in the Keynote Legend. As you can see in the image below, a plumbing fixture was keynoted and properly listed in the legend:
In another view, the cut plane and top plane were lowered until the element and keynote were no longer visible in the view::
In the above image, you can also observe that right-clicking the family type also reveals that the object is not visible in the view, yet it reports in the legend. Note that hiding the element and/or tag in the view makes the legend update accordingly, but in the above example the legend is misreporting.
This has been confirmed as a bug and slated for a future fix. In the meantime, please be careful and use this example to help in your troubleshooting efforts.