For most searches there is no difference in search behavior between command Find and command Find in Files. Make sure that all options including the Advanced options are set correct for your search. Is the correct directory specified? Is the correct file type specified? What about the standard options for Unicode search, match whole word only, match case and regular expression? Are any advanced Find in Files options enabled?
There are only 2 differences between command Find and command Find in Files.
The command Find is normally executed only on the current file, but can be also executed on all open files one after the one. So UltraEdit knows if the current file is a Unicode file (all types converted to UTF-16 LE for editing) or an ASCII/ANSI file and therefore runs the Find automatically either as Unicode or ASCII/ANSI search. But command Find in Files is mainly designed to run on not opened files. So for files encoded with UTF-16 LE or UTF-16 BE the option Unicode search must be enabled and for all other files standard ASCII/ANSI search must be used. Of course that means that using Find in Files for searching for UTF-8 or ASCII Escaped encoded characters is very difficult, but your search string does not contain any non ASCII character.
The second difference is only important if the search is a multi-line search, i.e. the search string contains line breaks. The command Find knows the type of line terminations for the current file (all opened files), but the Find in Files command is optimized for speed and therefore does not analyze which type of line endings the investigated files use. Find in Files is for a non regular expression search just a byte stream search and not a smart search like command Find which adapts the search string to the current file format and line terminations type. So when you run a multi-line Find in Files or Replace in Files and your files are not DOS files, you better replace the line breaks in your search/replace string(s) by ^n (UNIX) or ^r (MAC) or ^p (DOS) for non regexp or UE regexp searches respectively \n (UNIX), \r (MAC) or \r\n (DOS) for Unix/Perl regexp searches.