Missing file dialog box and finding the file.

see:

http://www.computer-darkroom.com/lr2_find_folder/find-folder.htm

You can select the name and copy it to the clipboard for later use in searching your disk

Many of us will not download attachments. Please include the screen capture in your reply by clicking on the "Insert Photos" icon.

Why does that informaiton need to go away when I hit the locate button?

We don't know why, we didn't design or program Lightroom Classic, we're just LrC users. Of course, you could write down the file name or make a screen capture of it.

A bigger problem is that you often have missing files in Lightroom Classic. This really shouldn't happen, it never happens to me, and it means some part of your workflow can be improved. If you are regularly moving or renaming photo files (or the folders that contain them) outside of Lightroom Classic, you should stop doing that. Of course, there may be other reasons for missing files.