Got caught because I didn't 'Check my assumptions'
Writing a filefind and it kept failing.
Thank fully 'Hot Reload' saved me some time while trying to find the problem.
Tearing my hair out 'cause it couldn't find "acad.lsp"
. . . . my assumption was that I actually had an acad.lsp on the search path

fwiw, the code :
public static bool FindFilePath(string FileName, out string path)
{
try
{
path = HostApplicationServices.Current.FindFile(FileName, _db, FindFileHint.Default);
}
catch (System.Exception ex)
{
_ed.WriteMessage($"\nException in 'FindFilePath({FileName})' :: {ex.Message}\n" );
_ed.WriteMessage("Ensure the file exists and it's location is on the ACAD File Search Path and a Trusted Location");
path = string.Empty;
return false;
}
return true;
}
usage:
if (FindFilePath("D:\\SD201_Config.INI", out string filePath))
{
_ed.WriteMessage($"\nQualified file path : {filePath}");
}