When instantiating at runtime, a simple prefab with GameFlow like this:

will throw

NullReferenceException: Object reference not set to an instance of an object GameFlow.Program._OnPrepare () (at <f07c123dcbb84a5c9a2fb7a216216afe>:0) GameFlow.Block.Prepare () (at <f07c123dcbb84a5c9a2fb7a216216afe>:0) GameFlow.GFBehaviour.PrepareBlocks () (at <f07c123dcbb84a5c9a2fb7a216216afe>:0) GameFlow.GFBehaviour.Start () (at <f07c123dcbb84a5c9a2fb7a216216afe>:0)

Actually duplicate an existing GameFlow gameobject in scene at runtime can reproduce this issue too.