When searching for a word–an option I love btw–sometimes it pulls up a scene or chapter, but doesn’t highlight anything.
FYI - When looking how to report a bug, I saw this:
Perhaps the most convenient way of reporting bugs, though, is to use the “Report Bug” feature available from Scrivener’s Help menu.
But I can’t see Report Bug on the Help Menu.
You are correct that report a bug is missing from the Help menu.
Ha, nice catch on the Report Bug mention.
As for the search highlight, unless you’ve changed the “Search In” parameters, Scrivener will be looking for the search term in various meta-data such as the label and keywords as well. So if your search term is “squid” and you have one document with the word “squid” in the body text and a second document with the label “squid”, both will be returned, but no text will be highlighted in the second. Could that be what’s happening?
My biggest bugbear is that find/search doesn’t work in full screen mode. 
That’s on the list and will be implemented, along with some other features that also don’t presently work in FS (mainly due to having no access to the menu at the moment).
Brilliant! 