If you type quotes in the search bar in the “find” pane, since it uses the system font, it makes fancy curly quotes.
These aren’t the same character as the monospace quotes in the editor, I guess, because this breaks any search that has quotes in it.
I think you should probably use the same font in the search bar that you use in the editor.
The same problem arises when typing double dashes—iOS applies apple’s auto-formatting and turns them into an emdash.