The binding is broken and the screen still looks fine

What this looks like

You bind a score label, press play, and the number never changes. The console is quiet. The screen shows the 0 or Score you typed in UI Builder, because a broken binding still leaves the element drawing its own text. That is why this one reaches you through a player report rather than QA.

Values that make the failure visible

Do not write design-time text that looks like a real value. Write a string that is obviously wrong when the binding dies.

1. Set the score label default to -- instead of 0.
2. Set the name label default to NO BINDING instead of Player.
3. A development-only background tint works too.

// Checking the binding itself is the reliable version
var label = root.Q<Label>("ScoreLabel");
if (label.GetBinding("text") is null)
    Debug.LogWarning("ScoreLabel has no text binding at runtime");

Half of it is when you attach the data source

A correct binding path does nothing while the data source is still missing. Compare when the UI document opens against when the game state is created. Usually the UI opens first and the first frame draws an empty value.

var document = GetComponent<UIDocument>();
document.rootVisualElement.dataSource = runtimeState; // after the state exists

How to check

1. Change the value at runtime and watch whether the label follows.
2. Deliberately leave the data source empty and look at the screen.
3. If that screen looks normal, fix the default text.

Expected result and next step

When an empty source produces an obviously wrong screen, this item is done. Lists are next: repeated items break through element reuse more often than through binding, so look at reuse in the scroll view separately.