Steps to reproduce
Put a tag in the notes field of a document title, #test. See attached screenshot. Search everywhere for that tag, #test. Search results show the document, but not the document title or highlighted search result. See attached screenshots.
Document title and highlighted search result in Search Everywhere
No document title or highlighted search result in Search Everywhere when searching for a tag in the document title notes.
Web, Windows 7 and 10, Chrome 57.0.2987.98
Probably not a common use case, but I sometimes use tags in the notes field of document titles as project notes, like for objectives and expected outcomes. On another attempt, I put the tag #test in the note field of an item and it shows in Search Everywhere, but the document title is still missing. Oddly, the document title shows up in the Android beta app, but not the highlighted search result.