Quick answer: Unreal Iris rollback restoring state without re-applying client-side spawn predictions? Rollback only handles confirmed state; predictions must be re-applied.
Player fires; predicts a bullet; rollback removes confirmed state; predicted bullet vanishes.
Re-apply predictions post-rollback
Cache predictions separately; replay after rollback.
Or include in rollback frame
State at frame N includes predictions for that frame. Rollback to N keeps predictions.
Audit prediction model
Each prediction: cached separately or in-state. Inconsistent = rollback bug.
“Predictions are local. Rollback is server. The two need explicit interaction.”
If your game has client prediction, the rollback-prediction interaction is a major design decision. Plan it.