This is a bug that is also present in Dota 2. I use tilde ( ` or ~) on the top left of my keyboard for a spell hotkey in both games. To be extra clear this is the key directly below the ESC key, to the left of '1' on the top row.
When a skill point is available, holding Alt and pressing the key does not level it like with all other keys. It's the same in dota 2; if you hold ctrl and press a hotkey it should level it, but this doesn't work with tilde. Much less annoying in Dota as I have learned to just click it, but in deadlock it's way moe annoying as you need to mouse over it with Alt held down.
When a skill point is available, holding Alt and pressing the key does not level it like with all other keys. It's the same in dota 2; if you hold ctrl and press a hotkey it should level it, but this doesn't work with tilde. Much less annoying in Dota as I have learned to just click it, but in deadlock it's way moe annoying as you need to mouse over it with Alt held down.