This .gif shows that the item doesn't come out of the chest, and instead comes out from the opposite direction. This is quite hard to reproduce, but exists in snapshot 70, for 1.6.4.

I will work on a stable reproduction of this, hopefully I can do that so that it is more easily fixed.

Ok, this seems to happen whenever you have a buffer placed within the actual relocator system like this:

In this case, the item does the same thing it does in the video above. There are no chunk boundaries. I can get the item to do that in pretty much any direction depending on Buffer placement.

I'll look into this, Buffers and Relocators don't seem to play nice together :(

I now see why this happens, but it's very hard to fix :S

Well, at least you found the source of the issue. If you want something a little easier 😄, you can look at the big list of issues, I added a few comments.