Search returns no results

I know that a folder contains files with (Original) in their name, but search doesn't show them. It showed a few at first, but never \ll of them.

This screenshot shows the problem:

I'm using the latest version of DOpus Pro (12.4) X.64.
Windows 10, intel core i7, 8gb Ram, 2tb harddrive, with 35% freee space.
Please let me know if you need more info,
Thanks in advance
Steve

(You don't need to use external hosting services to post screenshots - just drag & drop the image file directly into the post editor.)

What happens if you try that search in File Explorer? We just feed the supplied search string through to the Windows search engine; it's possible that brackets have special meaning to it and may need to be escaped in some way.