yes you are correct. I found the error- the PoolBoss was calling a function on my prefab before the "start" method on the Prefab had run. So I put the start commands into the function on the prefab. Then it worked OK. Thanks Matt
Yes, Start method is not guaranteed to run before the game object becomes inactive. Any state initialization code you should move out of Start (and Awake if it's there) and into OnSpawned, as the documentation states.