Quick answer: Unity 2D Rigidbody sleeping despite being pushed by a conveyor's friction surface? Sleep threshold beats applied force - set sleeping mode to NeverSleep on conveyored bodies.
Boxes on a conveyor belt: some move; others fall asleep and stop.
Set NeverSleep on conveyor zones
rb.sleepMode = RigidbodySleepMode2D.NeverSleep;Conveyors keep the body active despite low velocity.
Or wake on enter
OnTriggerEnter2D on the conveyor zone: rb.WakeUp(). Per-entry wake.
Tune sleep thresholds
Project Settings > Physics 2D > Velocity Threshold. Raise to keep slow bodies awake.
“Sleep is an optimization. Conveyors break the optimization's assumption.”
For any zone that imparts forces below the sleep threshold, NeverSleep is the right policy. Document; reuse.