Arrows are dropped rather than dispensed

What I expected to happen was for my Dispenser to fire regular arrows.

What actually happened was the arrows weren't dispensed from the dispenser, but were instead dropped, like if they had been fired from a dropper. The clock was slow enough to activate the dispenser(repeater + comparitor). Tipped arrows work fine, only regular arrows have this bug.

Steps to Reproduce:
1. Make a repeater + comparator clock as shown in screenshots
2. Place a dispenser in the circuit as shown
3. Fill dispenser with regular arrows
4. Turn on circuit, and arrow are dropped, instead of fired.