populate on object issue

[Dune]

Here's another riddle. I've made this farm, with an extra (invisible) roof object to populate straw on. When I make the pop-object with a few layers, the lower layers won't populate. When I make the lower layers into another object to populate on, it does work. So I have to use 2 pops on 2 objects, while I'd rather have just one pop on one object.

[Dune]

And the total roofpopper (of which lower parts won't populate) for you to play with, and a test of the setup.

[Kadri]

Is there rotation in your object you are populating? The bug is still around you know.

[Dune]

Yes, I use a vertical grassy object, rotate X 180º, and set rotation to -3 or so. But the object to pop onto is just as it is.

But the angle of the top part of the roof is the same as the other layers (which are only the lower areas), so they should populate as well. Unless the top part somehow masks out the populating of the lower parts....