Ctrl + 1 and Ctrl + 2 key combinations don't work

In my case this was caused by NVidia Geforce experience. It's not listed anywhere in the program under it's keyboard shortcuts - but uninstalling Geforce experience gave me my CRTL+1-3 keys back..

Great job Nvidia..

You could try and use Signo: it can tell you which application uses a certain hotkey, though not always; and if Activehotkeys doesn't see a hook, then I don't expect Signo to either - but who knows.

For more testing, you could download VirtualBox, make a virtual machine (that is easy), install Windows on this virtual machine, and test the hotkeys there. If they still don't work, then it is probably some weird hardware thing.

The Ctrl + 1 until 0 won't work if Windows is using them for changing keyboard layouts (English, Japanese, Norwegian and so on).

Go into the Control Panel (viewed by Category) » Clock, Language and Region » Change Keyboards or other Input Methods » Keyboards and Languages tab; Change Keyboards » Advanced Key Settings » Change Key Sequence for Ctrl + 1 until 0, to Shift + Ctrl + 1 until 0 or similar, depending on what you use.