First, we have to stop the currently running skhd process. We can do that with brew
brew services stop skhd
After this we can run skhd in verbose mode with skhd -V
After googling around, I found out that on “iTerm” the “secure keyboard entry” was enabled somehow. Probably due to me hitting random keyboard shortcuts around enabled it at some point.
After this I disabled Secure Keyboard Entry from iTerm menu and skhd keyboard shortcuts started working again.