Scriptui Button not working in 26.4.1

I have developed a relatively simple plugin with button click events. It was working fine till I updated the Illustrator till 26.4.1 - now even the simpliest button control objects (ok, cancel or simple alert function) do not work. The function is not called at all.

I don't think anything has changed in ScriptUI, what could that be?

example:
```

var b = win.add("button", undefined, "Test");

function alertFunction(e){

    alert(123);

}

```