Access voilation delphi x64 with callback's

Question

I rewrite old code (x86 ~ 1998 year, delphi 7) on new standart (x64, Rad Studio XE 10.4). I find problem place, which stopped my work. I create minimum example, that you can debugging (The structure of the code is strictly like this!):

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, ShellApi;

type
TTestProc = procedure(btn: TButton; i: Integer);

  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);

    procedure KeyDownTest();
    function FindNewFocused(): boolean;
    procedure Iterate(IterateProc: TTestProc);

  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}


procedure TForm1.Button1Click(Sender: TObject);
begin
  KeyDownTest();    // -->  KeyDownTest
end;

procedure TForm1.KeyDownTest();
begin
  FindNewFocused();  // -->  FindNewFocused
end;

function TForm1.FindNewFocused(): boolean;

  procedure IntNextVis(btn: TButton; i: Integer);
  begin
    ShowMessage(btn.Caption);  // ----> ERROR: ACCESS VOILATION!
  end;

begin
  Iterate(@IntNextVis); // -->  Iterate
  Result := True;
end;

procedure TForm1.Iterate(IterateProc: TTestProc);

  procedure IntIterate(btn: TButton; i: Integer);
  begin
      if(i > 2) then
        Exit;       // --> break reqursive
      if(i = 2) then
        IterateProc(btn, i) // -->  FindNewFocused.IntNextVis
      else
        IntIterate(btn, i + 1); // -->  Iterate.IntIterate
  end;

var
  i: Integer;
begin
    i := 0;
    //ShowMessage(Button1.Caption); // ----> WORKING!
    IntIterate(Button1, i);  // -->  Iterate.IntIterate
end;
end.

On Form there is button, pressed on which on screen will be write message like: Caption button. This code working without error on x86 platform, but broken on x64 platform. I look in debugger, stack trace and dissassembler (x64 platfrom!) and find error: when app call callback procedure IntNextVis(btn: TButton; i: Integer);, then in asm code args callback first transmitted, and than remove! Therefore, call ShowMessage(btn.Caption); is an not correct, as btn will be removed. My current configuration Debug. Why that going on and how fix this bug? P.S.: please, tell me solution this problem without move procedure IntNextVis of local area of visibility from global area of visiblity, as in my old code very very very mach such codes.