Sub AttemptSuccess3()
Dim oRng As Range
Dim oCC As ContentControl
  Set oRng = Selection.Range
  Application.CommandBars.ExecuteMso ("ContentControlDropDownList")
  oRng.End = oRng.End + 2
  Set oCC = oRng.ContentControls(1)
  With oCC
    .SetPlaceholderText , , "Select fruit"
    On Error Resume Next
      .DropdownListEntries.Item(1).Text = "Choose fruit from list."   'works anyway
    On Error GoTo 0
    .DropdownListEntries.Item(1).Value = ""
    .DropdownListEntries.Add "Apples", "Apples"
    .DropdownListEntries.Add "Blueberries", "Beets"
  End With
lbl_Exit:
  Exit Sub
End Sub

Sub AttemptSuccess4()
Dim oRng As Range
Dim oCC As ContentControl
  Set oRng = Selection.Range
  Application.CommandBars.ExecuteMso ("ContentControlDropDownList")
  oRng.End = oRng.End + 2
  Set oCC = oRng.ContentControls(1)
  With oCC
    .SetPlaceholderText , , "Select fruit"
    'Simply changing order of the following two lines seems to work and avoids the error.
    .DropdownListEntries.Item(1).Value = ""
    .DropdownListEntries.Item(1).Text = "Choose fruit from list."   'this works once
    .DropdownListEntries.Item(1).Text = "Choose fruit from list."   'errors if run a second time
    .DropdownListEntries.Add "Apples", "Apples"
    .DropdownListEntries.Add "Blueberries", "Beets"
    'Result: A fully functional DDL content control.
  End With
lbl_Exit:
  Exit Sub
End Sub