I think I'm almost there.  Can you check the code?  Is there that stands out as a potential problem?
    ' ...
' ...
 
On Error Resume Next
 
' Connect
Set session = WScript.CreateObject("WinSCP.Session")
 
 
Set sessionOptions = WScript.CreateObject("WinSCP.SessionOptions")
sessionOptions.Protocol = Protocol_SFTP
sessionOptions.HostName = "this.xx.gov"
sessionOptions.UserName = "username"
sessionOptions.Password = "xxxxxxx"
sessionOptions.SshHostKeyFingerprint = "ssh-rsa 2....."
 
If Err.number  > 0 Then
    Transfer_Succeeded_b = False
    ErrorNumber = Err.number
    ErrorDescription = Err.Description
    ErrorSource = Err.Source
    Err.Clear
    Call LogError( "Problem Assigning Session settings " & File_From_s & " to " & DESTINATIONFOLDER, ErrorNumber, ErrorDescription, ErrorSource )
End If
 
session.Open sessionOptions
 
If Err.number = 0 Then
    ' Upload files
    Set transferOptions = GetTransferOptions()
    Set transferResult = session.PutFiles( File_From_s, DESTINATIONFOLDER, False, transferOptions )
 
    ' Throw on any error
    transferResult.Check
 
    If Err.number  > 0 Then
       Transfer_Succeeded_b = False
       ErrorNumber = Err.number
       ErrorDescription = Err.Description
       ErrorSource = Err.Source
       Err.Clear
       Call LogError( "Problem Transferring " & File_From_s & " to " & DESTINATIONFOLDER, ErrorNumber, ErrorDescription, ErrorSource )
       Call SendErrorMessage( "Problem Transferring " & File_From_s & " to " & DESTINATIONFOLDER, ErrorNumber, ErrorDescription, ErrorSource )
    End If
 
    ' Returns false      
    Result_x = transferResult.IsSuccess()
 
    ' Returns the name of the file that attempted to send, even though it didn't succeed.
    For Each transfer In transferResult.Transfers
        Dim FileName_s
        FileName_s = transfer.FileName
        LogStatus( "Upload of " & transfer.FileName & " succeeded" )
    Next
Else
    Transfer_Succeeded_b = False
    ErrorNumber = Err.number
    ErrorDescription = Err.Description
    ErrorSource = Err.Source
    Err.Clear
    Call LogError( "Problem Opening Session for " & File_From_s & " to " & DESTINATIONFOLDER, ErrorNumber, ErrorDescription, ErrorSource )
    Call SendErrorMessage( "Problem Opening Session for " & File_From_s & " to " & DESTINATIONFOLDER, ErrorNumber, ErrorDescription, ErrorSource )
End If
 
' Disconnect, clean up
session.Dispose
 
' ...
' ...
 
' Earlier in the script, this function is defined
' No errors, and confirmed that the CONSTANTs are defined'
Function GetTransferOptions
    Dim TransferOptions_obj
 
    Set TransferOptions_obj = WScript.CreateObject( "WinSCP.TransferOptions" )
    TransferOptions_obj.TransferMode = TransferMode_Ascii
    TransferOptions_obj.OverwriteMode = OverwriteMode_Overwrite
 
    Result_x = TransferMode_Ascii
    Result_x = OverwriteMode_Overwrite
 
    Result_x = TransferOptions_obj.TransferMode
    Result_x = TransferOptions_obj.OverwriteMode
 
    If Err.number  > 0 Then
        Transfer_Succeeded_b = False
        ErrorNumber = Err.number
        ErrorDescription = Err.Description
        ErrorSource = Err.Source
        Err.Clear
    End If
 
    Set GetTransferOptions = TransferOptions_obj
End Function