Maybe a timing issue with the print spool. You might try:
Code:
Option Explicit
Public WithEvents oApp As Word.Application
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Private Sub oApp_DocumentBeforePrint(ByVal Doc As Document, Cancel As Boolean)
Application.ScreenUpdating = False
MsgBox "!"
Dim CCtrl As ContentControl, i As Long
With Doc
For Each CCtrl In .ContentControls
With CCtrl
If .Type <> wdContentControlPicture And .Type <> wdContentControlCheckBox Then
If .Range.Text = .PlaceholderText Then
i = i + 1
.Range.Text = "_________________________"
End If
End If
End With
Next
.PrintOut
DoEvents
Sleep 2000
.Undo i
End With
Cancel = True
Application.ScreenUpdating = True
End Sub