Hoppers facing north or west are moving items into mine cart chests and mine cart hoppers through thin air

What I expected to happen was...:
I expected the hopper to feed into the mine cart it was connecting to....

What actually happened was...:
the hopper fed into both the mine cart chest it was connected to and the one that was 1 block down and 1 block away from it

Steps to Reproduce:
1. place a hopper facing either north or west
2. place a mine cart chest or hopper as shown in the screenshots
3. shazam thin air transportation