Well your XML-Code works for me. Maybe the problem is something else? Aside from that I would also change the code to the following:
<ProgressBar
android:id="@+id/progressCircle"
style="?android:attr/progressBarStyleLarge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true" />
<TextView
android:id="@+id/txtvStatusCircle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@id/progressCircle"
android:layout_centerHorizontal="true"
android:text="Preparing..."
android:textSize="18sp" />
What's the difference? Order changed thus no "+id" is needed. Changed textSize qualifier to sp (you should always use this) and finally removed the "centerInParent" from the TextView since this isn't needed when you say "above my element in the center"