VBA

cherrypolisetti 

Private Sub Worksheet_Change(ByVal Target As Range)
    Dim ws As Worksheet
    Set ws = Me
    Dim selectedQueue As String
    Dim col As Integer
    Dim cell As Range
    Dim queueFound As Boolean
    Dim i As Long

    On Error GoTo ErrorHandler

    ' Handle queue selection in cell A1
    If Not Intersect(Target, Range("A1")) Is Nothing Then
        selectedQueue = ws.Range("A1").Value
        queueFound = False

        ' Unhide/hide columns based on queue selection
        Application.ScreenUpdating = False

        ' Loop through columns G to CZ
        For col = 7 To 104
            If ws.Cells(5, col).MergeCells Then
                Set cell = ws.Cells(5, col).MergeArea
                If Not IsError(cell.Cells(1, 1).Value) And Not IsEmpty(cell.Cells(1, 1).Value) Then
                    If Trim(CStr(cell.Cells(1, 1).Value)) = Trim(selectedQueue) Or Trim(selectedQueue) = "All Queues" Then
                        ' Unhide the columns if they are hidden
                        If cell.Columns.Hidden Then
                            cell.Columns.Hidden = False
                        End If
                        ' Select the first cell of the unhidden merged area
                        cell.Cells(1, 1).Select
                        queueFound = True
                    Else
                        ' Hide the columns if they are not the selected queue
                        cell.Columns.Hidden = True
                    End If
                End If
            Else
                ' If the column is blank, hide it
                ws.Columns(col).Hidden = True
            End If
        Next col

        ' If "All Queues" is selected, show all queues data
        If selectedQueue = "All Queues" Then
            For col = 7 To 104
                ws.Columns(col).Hidden = False
            Next col
            queueFound = True
        End If

        ' If the queue is not found, show a message
        If Not queueFound Then
            MsgBox "Queue not found in row 5."
        End If

        Application.ScreenUpdating = True
        Exit Sub
    End If

    ' Handle status changes and timestamping
    If Not Intersect(Target, Range("G6:G1000")) Is Nothing Then
        If Not IsEmpty(Target) Then
            ' Define headers and their corresponding columns
            Dim headers As Variant
            headers = Array("Status", "Commence", "Awaiting", "Re-Picked", "Completed")
            Dim headerCol As Variant
            Dim statusCol As Integer
            Dim timestampCol As Integer

            ' Find the header columns
            For i = LBound(headers) To UBound(headers)
                headerCol = Application.Match(headers(i), ws.Rows(6), 0)
                If Not IsError(headerCol) Then
                    If headers(i) = "Status" Then statusCol = headerCol
                    If Target.Column = statusCol Then
                        ' Get corresponding timestamp column
                        Select Case Target.Value
                            Case "Commence"
                                timestampCol = Application.Match("Commence", ws.Rows(6), 0)
                            Case "Awaiting"
                                timestampCol = Application.Match("Awaiting", ws.Rows(6), 0)
                            Case "Re-Picked"
                                timestampCol = Application.Match("Re-Picked", ws.Rows(6), 0)
                            Case "Completed"
                                timestampCol = Application.Match("Completed", ws.Rows(6), 0)
                        End Select
                        ' Insert timestamp
                        If Not IsError(timestampCol) And timestampCol > 0 Then
                            ws.Cells(Target.Row, timestampCol).Value = Now
                        End If
                    End If
                End If
            Next i
        End If
    End If

    Exit Sub

ErrorHandler:
    MsgBox "An error occurred: " & Err.Description
    Application.ScreenUpdating = True
End Sub

Corrected Code with Comments.

Placed On Error GoTo ErrorHandler at the beginning to cover the whole subroutine.

Added checks to ensure that Application.Match does not return an error before using the matched column.

My answers are voluntary and without guarantee!

Hope this will help you.