Control + Numpad Keybinding no longer working above N3

Bug Report reference #327665046

Very weird scenario, and this worked for ages up until today. So after the hotfixes last night.

I use a Naga mouse with 1-12 on the side. I've mapped those to the Numpad, and mapped my skills to use the first five of those buttons.

Skills 4-8 use Numpad 1-5. These are fine.
On the secondary skill bar, I have skills 9-13 set to use Control + Numpad 1-5. This worked fine until today.

For whatever reason, the client doesn't register Control + Numpad 4; all the up to 9. Tested by attempting to set the key combo again; it only registers Control. 1-3 still work perfectly normally.

I tested moving the skills around, so I know it's not the skills, it's definitely with the client registering those clicks. Tried restarting program, etc.

I do not know of any updates I had on any other windows program that could possibly be taking those keys, either. Happens with both actual numpad and my mouse buttons mapped to numpad. Control + Numpad key shortcuts on other programs like Chrome still work.