I recommended Karabiner Elements recently for MacOS key remapping. But after using it for a bit, I ran into an issue where it stopped working after my computer went to sleep or restarted.

It's a confusing bug, because the application still runs and shows no sign of an issue, but the remapped keybinds do not respond.

After a bit of tinkering and exploration, I found this Reddit comment that provided the solution for me.

Basically, I just need to run this command (twice for some reason), and then re-open Karabiner Elements and it works again.

sudo pkill -f Karabiner -9 # Kills the main Karabiner UI
sudo pkill -f karabiner -9 # Kills the background processes

It's a bit frustrating to have to continuously do as I rely on this software for my day-to-day work, but I'm glad there's a solution.

Hope it helps!