Rush Not Working

Hi everyone, this hasn't become a common problem yet but I just ran into someone who had this problem so I'm posting the solution that has worked for me twice in the past. This solution is for 4th job warriors who cannot use Rush despite having it on the hotkey or even through the skill window. To fix this:
The solution that fixed it was a CLEAN BOOT, not just a simple restart.

For windows 8.1 specfically, you had to:

1. Go to msconfig

2. System Config > Services
- Hide all Microsoft Services
- Disable all

3. System Config > Startup
- Open Task Manager
- Disable every Startup items
- Close Task Manager
- Press OK.

ADDITIONAL SOLUTIONS
-Navi told me that running/installing windows updates also fixes the problem. If both of these don't work I can do more research and update the guide ^^

-Autoassemble was using a VM and rebooting the VM worked for him. If you use a VM I recommend this option first.

-Credit doesn't belong to me but rather an old friend from a different server who quit long ago. Hopefully this helps anyone in the future that has this problem! Also props to Navi and Autoassemble for the methods they used.