Windows 10 minimizes program when I call set it to On Top - vb6

Question

This WORKS as expected on two Windows 10 systems (on a VM, the other a live PC). But on a third system (customer's, unfortunately) the form minimizes rather than being topmost.
SetwindowPos (TargetForm.hwnd, HWND_TOP,0,0,0,0, SWP_NOMOVE Or SWP_NOSIZE)
the Form (window) minimizes.
Any idea what would cause that?
This is a VB6 program (don't laugh!, I make a living on this program :)
UPDATE:
More details on code:
Set FormActive = frmToShow
frmToShow.Show
FormZorderSet frmToShow, Z_top
If Not frmPrevious Is Nothing Then
frmPrevious.Hide
End If
Public Function FormZorderSet(frmTarget As Form, Zorder As FormZorderType) As Long
FLAGS = SWP_NOMOVE Or SWP_NOSIZE
FormZorderSet = SetWindowPos(frmTarget.hwnd, Zorder, 0, 0, 0, 0, FLAGS)
Global declares
Public Declare Function SetWindowPos Lib "User32" (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long
Const SWP_NOSIZE = &H1
Const SWP_NOMOVE = &H2
Const HWND_TOPMOST = -1
Const HWND_TOP = 0

Answer 1

Try using this ontop function
'moudle code
Option Explicit
Public Const SWP_NOMOVE = 2
Public Const SWP_NOSIZE = 1
Public Const FLAGS = SWP_NOMOVE Or SWP_NOSIZE
Public Const HWND_TOPMOST = -1
Public Const HWND_NOTOPMOST = -2
Declare Function SetWindowPos Lib "user32" _
(ByVal hwnd As Long, _
ByVal hWndInsertAfter As Long, _
ByVal x As Long, _
ByVal y As Long, _
ByVal cx As Long, _
ByVal cy As Long, _
ByVal wFlags As Long) As Long
Public Function SetTopMostWindow(hwnd As Long, Topmost As Boolean) _
As Long
If Topmost = True Then 'Make the window topmost
SetTopMostWindow = SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, 0, _
0, FLAGS)
Else
SetTopMostWindow = SetWindowPos(hwnd, HWND_NOTOPMOST, 0, 0, _
0, 0, FLAGS)
SetTopMostWindow = False
End If
End Function
Then for the use
'use
Dim lR As Long
Private Sub Form_Load()
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'set form to allways on top
lR = SetTopMostWindow(Me.hwnd, True)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
End Sub
This has worked for me in windows 10 without it minimizing my program.