OverFlow Error only on Apple M1 Pro When Resizing Userform

[truk]

I have a excel project that has been running successfully on Windows and Mac for sometime.

One of the steps includes resizing a userform if the user is on a Mac. The user is prompted, and can choose 'yes' or 'no' to resize forms.

This was fine until a couple of users bought a new 14 inch M1 Macbook Pro (2021) running Monterey
These users and ONLY these users reported getting an overflow error (Runtime error 6) if they allow the resizing.

Interestingly...
The error DOES NOT occur if the user is displaying the workbook on an external screen.
The error DOES NOT occur if the code is manually stepped through.
The error DOES NOT occur on older mac models (has functioned on High Sierra through to Big Sur)

Any suggestions would be greatly appreciated.

Calling code in the user form

Private Sub UserForm_Initialize()
    #If Mac Then
        If MsgBox("Use MAC form resizing?", vbYesNo) = vbYes Then
            ResizeUserForm Me
        End If
    #End If
    'other code
End Sub

Resizing sub in a standard module

Option Explicit

Public Const gUserFormResizeFactor As Double = 1.4
'Global variable used as plan is to allow users to manually adjust resizing in some circumstances. This is not yet implemented.

'intermittant error on calling this sub
Public Sub ResizeUserForm(frm As Object, Optional dResizeFactor As Double = 0#)
'https://peltiertech.com/userforms-for-mac-and-windows/
    Dim ctrl As Control
    Dim sColWidths As String
    Dim vColWidths As Variant
    Dim iCol As Long
    
    If dResizeFactor = 0 Then
        dResizeFactor = gUserFormResizeFactor
    End If
    With frm
        .Height = .Height * dResizeFactor
        .Width = .Width * dResizeFactor
        
        For Each ctrl In frm.Controls
            With ctrl
                .Height = .Height * dResizeFactor
                .Width = .Width * dResizeFactor
                .Left = .Left * dResizeFactor
                .Top = .Top * dResizeFactor
                On Error Resume Next
                .Font.Size = .Font.Size * dResizeFactor
                On Error GoTo 0
                
                ' multi column listboxes, comboboxes
                Select Case TypeName(ctrl)
                    Case "ListBox", "ComboBox"
                        If ctrl.ColumnCount > 1 Then
                            sColWidths = ctrl.ColumnWidths
                            vColWidths = Split(sColWidths, ";")
                            For iCol = LBound(vColWidths) To UBound(vColWidths)
                                vColWidths(iCol) = Val(vColWidths(iCol)) * dResizeFactor
                            Next
                            sColWidths = Join(vColWidths, ";")
                            ctrl.ColumnWidths = sColWidths
                        End If
                End Select
            End With
        Next
    End With
End Sub

[truk]

Problem has been solved by changing

Public Sub ResizeUserForm(frm As Object, Optional dResizeFactor As Double = 0#)

to

Public Sub ResizeUserForm(frm As Object, Optional dResizeFactor As Variant = 0#)

This is quite irritating as I can see no reason why the double type should have thrown the error, or why the error should have occurred in only in such specific circumstances.

[Aussiebear]

Thank you for posting the solution