For some reason now whenever I open livesplit and press num pad 1 or any hotkey I put start to it doesn't work unless I press the timer itself and not press anything after

Looks like you need to enable "Global Hotkeys" in the settings.

Global Hotkeys should solve the issue, though I have had problems with at least one game seemingly overriding those global hotkeys. Doesn't seem like that's their problem though.

I've had the same issue with having to focus the livesplit window for it to register my hotkeys.

In my case, enabling "Global Hotkeys" didn't work for me and instead running livesplit as administrator in conjunction with global hotkeys allowed it to work^^