"Stay on top" main form and modal dialogs in Delphi XE

In Delphi XE Update 1, I’m getting seemingly random behavior of modal forms if the parent (main) form’s FormStyle is set to fsStayOnTop.

1) With MainFormOnTaskbar := False (the old way), everything “just works”. With the new MainFormOnTaskbar := True, modal forms get hidden behind the main form when the main form is set to “stay on top”. In most cases saying

modalForm.PopupParent := self;

just before the call to modalForm.ShowModal seems to help. But not always.

2) All my modal forms are simple, no frills, positioned at MainFormCenter, not using form inheritance, etc. And yet the PopupParent fix only works for about half of them, while the other half still get hidden behind the main form. Strangest of all, in one case the ordering of unrelated lines of code breaks or makes it. See lines marked (1) and (2) in this code:

procedure TEchoMainForm.DBMaintenancePrompt( actions : TMaintenanceActions );
var
  frm : TDBMaintenanceForm;
begin
  frm := TDBMaintenanceForm.Create( self );
  try
    frm.Actions := actions; // (1)
    frm.PopupParent := self; // (2)
    frm.ShowModal;
  finally
    frm.Free;
  end;
end;

When executed in this order, the modal form shows correctly on top of the main form. But when I reverse the lines, the modal form hides behind main. The line marked (1) sets a property of the modal form, which results in several checkboxes being checked on unchecked in a TRzCheckGroup, sitting on a TRzPageControl (from Raize components). This is the setter method that runs when line (1) above executes:

procedure TDBMaintenanceForm.SetActions(const Value: TMaintenanceActions);
var
  ma : TMaintenanceAction;
begin
  for ma := low( ma ) to high( ma ) do
    cgMaintActions.ItemChecked[ ord( ma )] := ( ma in Value );
  end;
end;

This is enough f