Subfolder depth -- doesn't work passed 0?


Hello,
I have a folder structure like this:
Folder
-1
---a
---b
---c
-2
---d
---e
---f
-3
---g
---h
---i
where 1, 2, and 3 are directories, and a-i are images.
The rule I attached is on the directory called "folder", which contains 1,2, and 3. If I set subfolder depth to 0, it will delete images in "folder", but if I set subfolder depth to 1, it will not delete images in 1,2, or 3.
How can I make it delete images in 1,2, and 3? I think I'm misunderstanding how the subfolder depth trigger works.
Thanks
