Discrete Scrolling Inconsistent

Enabling 'Discrete Scrolling' doesnt fix the hotbar often failing to scroll 

What I expected to happen was...:
The hotbar to scroll to the next slot whenever I use the mouse wheel

What actually happened was...:
Inconsistently completely ignores input until I stop scrolling and retry

Steps to Reproduce:
1. Enable OR Disable 'Discrete Scrolling'
2. Use the mouse wheel to scroll through the hotbar