Assistance Needed with VBA Code for Copying Data

All parts that look like this:

.Range("G4", Range("G" & Rows.count)

should be changed to

.Range("G4", .Range("G" & .Rows.count)

Declare a new variable

Dim rngCopy As Range

Change all sets of lines like this:

.Range("G5", .Range("G" & .Rows.count).End(xlUp)).SpecialCells(xlCellTypeVisible).Copy
wbMaster.Worksheets("CS_Export").Range("L2").PasteSpecial xlPasteValues

to

Set rngCopy = .Range("G5", .Range("G" & .Rows.count).End(xlUp))
If rngCopy.Count > 1 Then
    Set rngCopy = rngcopy.SpecialCells(xlCellTypeVisible)
End If
rngCopy.Copy
wbMaster.Worksheets("CS_Export").Range("L2").PasteSpecial xlPasteValues

P.S. The code refers to a worksheet OS that is not present in the workbook that you attached.

The macro should end like this, so that ScreenUpdating and DisplayAlerts are set even if an error occurs. (Why do you want to set DisplayAlerts to False at the end, by the way?)

Exit_handler:
    With Application
        .ScreenUpdating = True
        .DisplayAlerts = False
    End With
    Exit Sub

Error_handler:
    MsgBox "An error has occured while processing the file. Please close the file and rerun it, if the problem persists contact the CE support team"
    Application.Calculation = xlAutomatic
    Resume Exit_handler
End Sub