Quick answer: Scene view → Effects dropdown → tick Animated Materials. Prefab thumbnails render only a single frame and never animate; that’s expected. For deterministic time, expose a Custom Time property and SetVector from script.

Time node feeds a sine driving an emissive pulse. Game view: pulses correctly. Scene view: stuck on whatever value Time happened to be. Prefab thumbnail: stuck on a different value. Three views, three behaviors, two fixes.

The Symptom

Shader Graph using a Time node animates correctly in Play Mode and Game view, but Scene view shows it frozen. Prefab thumbnails in Project window show the material lit but unanimated. Editor previews of the shader show motion.

What Causes This

Three different rendering paths handle Time differently:

The Fix

For Scene view: Open the Scene view. Click the Effects dropdown (the gizmo at the top right of the Scene view toolbar). Tick “Animated Materials.” Time now ticks in Scene view. Behavior persists per Scene window.

For prefab thumbnails: Accept that they’re a single-frame snapshot. To preview the animation in the project, drag the prefab into the open Scene and view it there with Animated Materials on.

Custom Time for Determinism

Built-in _Time is global and starts at scene load. For replays, networked games, or animations that must sync across machines, drive Time yourself.

In Shader Graph: add a Vector4 property named _CustomTime (or anything). In the graph, replace the Time node with this property. Time.x = elapsed seconds, .y = sin, .z = cos, .w = delta — or just use .x.

From script:

public class DriveShaderTime : MonoBehaviour
{
    public Renderer rnd;
    private MaterialPropertyBlock _mpb;
    private static readonly int _id = Shader.PropertyToID("_CustomTime");

    void Start() { _mpb = new MaterialPropertyBlock(); }

    void Update()
    {
        var t = MyGameClock.NetworkTime;
        _mpb.SetVector(_id, new Vector4(t, Mathf.Sin(t), Mathf.Cos(t), Time.deltaTime));
        rnd.SetPropertyBlock(_mpb);
    }
}

Now the shader sees your clock, not Unity’s, and pause/replay/scrub work correctly.

Verifying

Scene view with Animated Materials on: pulses visible. Without: frozen. Game view with the script: pulses match your clock. Pause your clock; pulses freeze.

Understanding the issue

Shader bugs manifest visually but trace to invisible state. Triage requires understanding the runtime context as much as the source.

The specific bug described above is the kind that surfaces during integration rather than unit testing. It depends on a combination of factors: the asset configuration, the runtime state, the platform's specific behavior. In isolation, each piece looks correct; in combination, the bug emerges. This is why thorough integration testing - playing the actual game in realistic conditions - catches things that automated tests miss.

Why this happens

Bugs of this class are particularly easy to ship past internal QA because they often depend on specific runtime conditions - hardware combinations, network states, or asset configurations that QA didn't reproduce. Players hit them in the wild, file reports that are hard to repro, and the bug accumulates negative reviews while engineering tries to recreate the failure mode.

At the engine level, the behavior comes from a deliberate design decision in Unity. The engine team chose a particular trade-off - usually performance versus convenience, or generality versus specificity - and that trade-off has consequences when you push against it. Understanding the trade-off is what turns 'this bug is mysterious' into 'this bug is the expected consequence of this design'.

Verifying the fix

After applying the fix, the verification step has three parts: confirm the original repro is resolved, confirm no obvious regressions in adjacent functionality, and (for shipping titles) deploy to a small player cohort first and watch the crash and report rates. Each step catches something the others miss.

Reproducibility is the prerequisite for verification. If you can't reliably reproduce the bug pre-fix, you can't reliably verify it post-fix. Spend time getting a clean reproduction before you write any fix code. The fix is fast once you understand the reproduction; the reproduction is the slow part.

Variations to watch for

There's almost always a less obvious case where the same problem applies. The reported case is the one a player hit; the related cases hide because they're rarer or affect fewer players. After fixing the reported case, search the codebase for the pattern - one fix often unlocks several.

Adjacent bugs often share a root cause. After fixing the case you've found, spend an hour searching the codebase for similar patterns. What's the same call with different arguments? The same data flow with a different entity type? The same lifecycle issue in a sibling system? Each match is a candidate for the same fix, or a related fix that prevents future bugs of the same class.

In production

Live games surface this bug class at scale. What's a rare edge case in development becomes a daily occurrence once you have a few thousand concurrent players. The class isn't 'this player has a unique setup'; it's 'one in N thousand sessions will trigger this exact combination'.

When triaging a similar issue in production, prioritize gathering data over hypothesizing causes. A player report describes a symptom; what you need is a build SHA, a session timestamp, and ideally a screen recording or session replay. With those, the bug becomes tractable. Without them, you're guessing at hypothetical reproductions that may not match what the player actually hit.

Performance considerations

Performance implications matter when this bug class scales with player count or asset count. A bug that fires once per session is annoying; a bug that fires once per frame compounds. After fixing, profile the affected code path under realistic load. The fix that's correct for one entity may be too slow for ten thousand.

Diagnostic approach

The diagnostic tools available depend on your engine and platform. Use the engine's native profilers and debug overlays before reaching for external tools. The native tools have context that external tools lack - they know which subsystem owns the code, which assets are loaded, and what state the engine is in.

For Unity-specific diagnostics, the editor's profiler is the canonical starting point. Capture a representative frame with the symptom present; compare against a frame without the symptom; the diff often points directly at the cause. If the symptom is non-deterministic, capture multiple frames and look for the pattern - the cause is usually a state transition or a specific input value rather than a continuous effect.

Tooling and ecosystem

Third-party plugins often provide better diagnostics for their own behavior than the engine does. If the affected code is in a plugin, check the plugin's documentation for debug modes, verbose logging, or inspector tools - these can save hours of investigation when they exist.

Within Unity, the relevant diagnostic surfaces include the standard frame debugger, memory profiler, and engine-specific debug overlays. Each one shows a different facet of what's happening. The frame debugger reveals draw call ordering and state transitions; the memory profiler shows allocation patterns; the debug overlay reveals per-system state. Bugs that resist one tool usually surrender to another - the trick is knowing which tool to reach for first.

Edge cases and pitfalls

Edge cases for this class of issue often involve specific timing: the first frame after a state change, the last frame before a transition, frames where multiple subsystems update simultaneously. Reproducing these reliably is part of what makes the bug class hard to test.

When writing a regression test for this fix, focus on the boundary conditions that surfaced the original bug. Tests that exercise the happy path catch obvious regressions; tests that exercise the boundary catch the subtler regressions that look like new bugs but are really the original returning. The latter are the tests that earn their keep over the long life of the project.

Team communication

When this bug class affects multiple teams (often the case for cross-system issues), early communication prevents duplicate work. The team that owns the symptom may not own the cause. A 15-minute conversation at the start of triage often saves hours of independent investigation.

If this fix touches a system several engineers work in, a short writeup in the team's engineering channel helps. Not a full design doc - a paragraph explaining what was wrong, what's fixed, and what to watch for. Future engineers encountering similar symptoms will search for the fix; making it findable is a small investment that pays back later.

“Animated Materials for Scene. Custom Time for everything else. Thumbnails are a snapshot, not a preview.”

Related Issues

For Shader Graph not updating in build, see build shader updates. For shader properties not applying, see exposed property.

Animated Materials. Custom Time when it matters. Thumbnails stay still.