Yes, UltraEdit does not have a search option to find/replace strings encoded in UTF-8 in not opened files. A workaround is to open all UTF-8 files and run the find/replace in all open files.

Another workaround would be to create an UTF-8 file with the search and replace string you want to use, save and close this UTF-8 file, disable the auto detection of UTF-8 files in the configuration and re-open the just saved UTF-8 file. Now you see the search and replace strings as ASCII/ANSI and therefore you can run the Find In Files or Replace In Files command with those strings. This is an extremly complicated workaround and surely not useful for daily use.

I completely understand why you need a Find/Replace In Files using UTF8. And I have even written a feature request email long time ago (March 2006) to IDM for additional options for the Find/Replace In Files command. But it seems I was the only one.

Well, that missing support for searching UTF-8 strings or strings in OEM character set (entered in ANSI) or text strings searched in hex does not really bother me because I use "Total Commander" for file management and it's "Find Files" feature can nearly everything. So I can always use Total Commander to find the files of interest and when the list of found files is not enough because I want to see also the lines where a string is found or I want to modify the found strings, I can drag and drop the files from the found list box of Total Commander into UltraEdit and run the find or replace in UltraEdit on all open files.