Why is StreamReader.ReadLine() and File.ReadAllText() returning null or empty

Question

I did find a few similar questions, but they weren't able to point me in the right direction... This may be something entirely stupid, but if anyone could tell me why I can't get a string populated I'd appreciate it. Here's my method that's failing:

private static string passwordTrace { get; set; }

// ... lots of other code

private static void RefreshPassword()
    {
        try
        {
            string filePath = "\\\\[server ip]\\share\\folder\\file.abcd";
            string npDecrypted;
            DateTime lastRefreshDate = Properties.Settings.Default.lastRefresh;
            if (DateTime.Now >= lastRefreshDate.AddDays(30))
            {
                using (StreamReader sr = new StreamReader(filePath))
                {
                    string npEncrypted = sr.ReadLine();
                    if (npEncrypted.Length != 24)
                    {
                        string fr = File.ReadAllText(filePath);
                        npEncrypted = fr.Substring(0, 24);
                    }

                    npDecrypted = Decryptor(npEncrypted);
                    passwordTrace = npDecrypted; // added for debugging only! remove when done.

                    secureString npSecure = new SecureString();
                    foreach (char c in npDecrypted)
                    {
                        npSecure.AppendChar(c)
                    }
                    Properties.Settings.Default.adminpw = npSecure;
                    Properties.Settings.Default.Save();
                }
            }
        }
        catch (FileNotFoundException fnfe)
        {
            // code for handling this type of exception
        }
        catch (NullReferenceException nre)
        {
            // code for handling this type of exception
        }
        catch (Exception e)
        {
            // code to catch ANY other type of exception
        }
    }

Now, there are no errors or warnings when the VS debugger compiles everything, and it works correctly when debugging. But, if I copy the compiled exe (from C:\project\bin\Debug directory) and run it the issue arises.

The point that says passwordTrace = ... is called at another point by a message box. This works correctly when running via debugger and there aren't any exceptions thrown anywhere (I do have try/catches all over the place), but for whatever reason the PasswordTrace and the Properties.Settings.Default.adminpw don't seem to be holding their value throughout the applications execution.

Also, the file that is being read is an encrypted text file which will always have only 1 line of characters and that line is always 24 characters long. An example would be:

09sdjf09ausd08uf9!%38==

As a final statement, I also copied the app.exe.config and app.pdb to the server directory where I copied the compiled .exe file to see if that had anything to do with it and it didn't fix anything. I also tried running the .exe directly from the Debug directory (the same file that I'm copying elsewhere) and it works correctly. As soon as I move it off of the Local Disk it doesn't work.

So, my suspicions are that it has something to do with the environments working directory, or something to do with how the app is executing. I read something somewhere that noted the default users is not set, but I think that was specifically regarding ASP.NET. If that was the case and the user double-clicking on the .exe didn't have a proper network authentication then what would I do? And if it has something to do with the working directory, how can I circumvent this?

I'm gonna keep fiddling and if I figure it out I'll update this, but I'm so lost at the moment! lol! And for the last time - everything it/was working correctly until copying it to the server location.

Thanks in advance! :)