GPU particles "colliding" with objects in front of it

Please excuse the confusing title but I have some troubles figuring out the issue.
I’m using the GPU typedata so I can have large amounts of particles and I’m running into some issue when collision is toggled on.

Here it’s acting as it should, the particles are killed once they hit the cube, and as you can see the little rectangle on the right isn’t in the path of the particles, so it doesn’t affect them.

But if I move the camera behind the mentioned rectangle, the particles stop short and are killed.

140005-a0576d4665.jpg

As I said before, the same events happen regardless of whether I’m using stop, bounce or kill as collision response.
I’m looking to understand better why that happens and if I can do anything about it, as far as I know GPU particles use scene depth to calculate collisions, so maybe it’s just the way it works and I can’t do anything about it, but still it feels like something is off.

Update : checked once again, and it actually bounces in the case where it’s set to bounce, I thought wrong.