Hopper Clocks Broken (16w43a)

Problem: Simple hopper clock does not update comparators. North and East side hopper keeps the comparator on. South and West side hopper keeps the comparator off.

Expected Behavior: Opposite facing comparators should flash on/off – off/on.

Steps To Duplicate: Point two hoppers into each other add 1 item. Add comparators to detect the item in each hopper.