my "ground2" object is spawned by 3 "spawner_blocks2" the bonus is also spawned by the 3 same "spawner_blocks2"
All I'm saying is..
Could it be the bonus is spawned by a spawner_blocks2 instance that hasn't spawned a ground-object?
A random instance of the spawner_blocks2 is picked for spawning the bonus..
If this instance hasn't spawned a ground2 object at the exact same time, the bonus won't be over a ground2 object..
You could always choose to have a ground2 object spawn the bonus, that way it would always be above a ground2 object..