Additionally You can find a great explanations by Mitsos here,
read thread from this post down: Bloom dont work or why my trash is empty? - #36 by Mitsos
Also we have official explanations, what actually happened here:
https://forum.storj.io/t/current-situation-with-garbage-collection
That’s shines a lot of light to the situation.
In short, from now on, the situation should be getting better and better by the week!