droppers refuse to fire when hooked up to a comparator clock above y level 59

The droppers are hooked up as shown in the picture, if the redstone line crosses a chunk boundary above y = 59, it won't rapid fire the droppers.

 

Below y=59 the droppers fire as normal even when the redstone line crosses a chunk border

if the comparator clock is split between chunk borders, the dropper also won't fire regardless of y coordinates