Android Studio – Progressbar is not changing progress in loop

I have problem with changing status in my progress bar on my app.
I have while loop which is changing status from 1-100 every 100ms.
Loop works cause when I’m making Log checker which shows how much is actually equals "I" it’s from 1-100.
When i’m putting manualy progress to for example 50 it shows but nothing change.

class StartActivity : AppCompatActivity() {

    private var progressBar: ProgressBar? = null
    private val handler = Handler()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_start)


        progressBar = findViewById<ProgressBar>(R.id.progressBar_activityStart)

        startProgressBar()
    }

    private fun startProgressBar() {
        progressBar!!.visibility = View.VISIBLE
        var i: Int = progressBar!!.progress
        progressBar!!.progress = 0

        Thread {
            while (i < 100) {
                i += 1
                handler.post {
                    progressBar!!.progress = i
                    Log.v("progress", i.toString())
                }
                try {
                    progressBar!!.progress = i
                    Thread.sleep(100)
                } catch (e: InterruptedException) {
                    e.printStackTrace()
                }
            }
            progressBar!!.visibility = View.INVISIBLE
        }.start()
    }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    tools:context=".StartActivity">

    <ImageView
        android:id="@+id/imageView_activityStart_logo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@color/white"
        android:layout_centerInParent="true"
        android:src="@drawable/logohorizontal" />

    <ProgressBar
        android:id="@+id/progressBar_activityStart"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/imageView_activityStart_logo"
        android:layout_alignBottom="@+id/imageView_activityStart_logo"
        android:layout_marginStart="30dp"
        android:layout_marginTop="30dp"
        android:layout_marginEnd="30dp"
        android:layout_marginBottom="30dp"
        android:indeterminate="false"
        android:visibility="visible" />

</RelativeLayout>