Ctrl + Alt + Arrow key doesn't switch workspaces

My Ctrl+Alt+Arrow key fails to switch my workspace, but this is only true if

1. NumLock is on
2. I press Ctrl followed by the Alt key
3. I'm using the left Alt key
4. I'm logged in as me (as opposed to a guest)

Any help debugging this weird behavior would be greatly appreciated. It's a pretty frustrating little bug that gets in my way at least 20 times a day, and it's so strange that I would really just like to understand how it could be happening, although I wouldn't mind just fixing it with some kind of keybindings/unity/compiz reset. I just need some pointers on how to achieve this reset. Thanks!

Solution 1:

I've solved it by enabling Desktop Wall in CompizConfig Settings Manager:

Solution 2:

In my case, the problem had to do with a conflict between the Desktop Wall plugin and the Grid plugin. After I invoked Compiz Config Settings Manager (CCSM), and I unchecked and checked Desktop Wall, CCSM gave me the option of disabling the key bindings of the Grid plugin that conflicted with Desktop wall. To be safe, I disabled the Grid plugin. My Ctrl+Alt+Arrow keys are working fine now.

Solution 3:

I've you've come here (like me) for the title alone (Ctrl+Alt+Arrow key doesn't switch workspaces) then additionally to other answers here, try increasing the SIZE of your desktop:

Compiz > General settings > "Desktop size" tab > if it's 1x1, increase it

Credit to Uchiha Madara's comment in another question.

Solution 4:

I had a similar problem running on a virtual machine and it turned out that VMWare Workstation was capturing Ctrl +Alt +Left/Right to switch between active virtual machines.

In WMWare Workstation > Virtual Machine > Preferences > Hot Keys, I changed the hot key combination to Ctrl+Alt+Windows Key.