Quick answer: Unity Prefab Stage edits vanishing after closing the stage? Stage edits aren’t auto-saved — press Ctrl+S inside the stage before closing.
Editing a prefab in Prefab Stage; the user closes the stage without saving. Changes are lost.
Explicit Save
Prefab Stage is isolated — changes apply only when saved. File → Save (Ctrl+S) inside the stage writes the prefab. Closing without save shows a prompt; clicking discard loses work.
Save Prompt Settings
Preferences → General → Save Prefab Without Asking. Disable for confirmation prompts; enable for power users who save constantly.
Auto-Save Pattern
Custom editor scripts can subscribe to PrefabStage.prefabSaving and re-save automatically on some triggers. Use sparingly.
Working Outside Stage
Edit on instances in the scene, then Apply All Overrides to push to the prefab. Alternative workflow that doesn’t require Stage entry.
Verifying
Edit, save, close — reopening shows the saved state. No accidental discards.
“Prefab Stage is sandboxed. Save before close or lose the edits.”
If your team loses edits often, enable Save Prefab Without Asking — safer to save than to lose.