>So far, I have no problem searching with Code Reference except for this case. As I have mentioned, for the same string being searched, once the scx or vcx file is renamed, the search is done correctly... so it is not a pure searching problem, I feel like something else is blocking the search in those files, I just can't be sure what is that?

I think you are correct in that it will not search a file that is already open and in memory. I've seen that behavior before in VFP when trying to copy files.