Extendscript UI "tabbedpanel" children not centered

Hi everyone,

I made an After Effects script that contains a tabbed panel.

This panel's childrens are centred while I run the script on CS6.

However, when I launch it on CC2019, the panels are not centred.

var myWindow = new Window ("palette", "Motion Engine v1.2", undefined);

myWindow.Orientation = "row";
myWindow.alignChildren = "center";

var logoPath='/e/Dev/Scripts/Motion Engine/Logo/ME Logo Small.png';
var logoGroup = myWindow.add("image", undefined, logoPath);

var tPanel = myWindow.add ("tabbedpanel");
tPanel.alignChildren = ["fill", "fill"];

var insertTab = tPanel.add ("tab", undefined, "Insert Transitions");
insertTab.alignChildren = "center";

var modifyTab = tPanel.add ("tab", undefined, "Modify Transitions");
modifyTab.alignChildren = "center";

So, I'm wondering how could I make the panels centered in any version.

Thanks.