Quick answer: Assign the SpriteRenderer an explicit Sorting Layer and Order in Layer, and use a Sorting Group on multi-part animated characters so their internal order stays consistent.
An effect sprite that should pop in front of the character instead vanishes behind it, or a UI overlay sits under the action. SpriteRenderers ignore hierarchy order entirely; they sort by layer and order values you must set deliberately.
How to fix it
1. Set Sorting Layer and Order in Layer
On the SpriteRenderer, pick a Sorting Layer (define a stack in Project Settings) and an Order in Layer. Higher orders draw on top within the same layer.
2. Wrap multi-part characters in a Sorting Group
Add a SortingGroup component to a character built from several animated sprites so they sort as a unit against the rest of the scene and do not interleave with other objects.
3. Keep UI on a Canvas, not sprites
World-space sprites and Screen Space UI use different systems; put HUD elements on a Canvas with a higher sort order rather than trying to layer them as sprites.
Catching the ones you can't reproduce
The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.
Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.
This is where a tool like Bugnet earns its place. Its SDK captures every Unity error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.
Ship the fix, watch the signature disappear from the next build. That's how you know it's really gone.