Thanks SHG,

I was hoping for a less brute force approach, but couldn't find one. So now I've written in a ton of Unprotect/Protect sequences to make it work. Corrected Macro code is below. 
Private Sub Worksheet_Change(ByVal Target As Range)
Dim ws As Worksheet:    Set ws = Sheets("View1Pivot")
Dim ws2 As Worksheet:   Set ws2 = Sheets("Chart-View 1")


If Target.Cells.Count > 1 Or IsEmpty(Target) Then Exit Sub

    If Target.Address = "$E$1" Then
    ws.unprotect
    ws.Range("N:N").AutoFilter Field:=1, Criteria1:=ws2.Range("E1").Text
    ws.protect
End If

End Sub
Thanks for pointing me in the right direction.