I came across this question while trying to solve a problem: Child actor components don't spawn on clients - C++ - Unreal Engine Forums
Basically I was having problems trying to spawn an actor that had child actor components in its blueprint. Frustratingly, the child actor property of the child actor component was set to null on all of the clients, even though the object was visible on the client screen. Even worse, the value would not be null seemingly randomly about 1% of the time.
My solution was to turn off replication on the child actor class, and turn on replication on the child actor component as noted in the linked question. I also needed to make sure Net Load on Client was turned on in the child actor class to support anything that was placed in the scene and not spawned dynamically. This is very unintuitive and feels like it may be a bug. I’m wondering why this is, and if there’s a better solution.