(Left) Ctrl + Shift + Down is not working but (Right) Ctrl + Shift + Down does

The left ctrl + shift + down arrow key is not working while the right side does. Any ideas why?

I have gone to settings -> apps -> installed apps -> Microsoft 365 Copilot -> advanced options, then clicked repair. But nothing happened.

I also have restarted my PC to make sure that no other program is affecting the shortcut keys, but it's still not working.

Edit:

Ctrl + Shift + other arrow keys, do still work for both sides. It's just down key on the left side.

Using the on screen keyboard works as well.