Ctrl + Shift + L keyboard shortcut not working

According to Auto-fill logins using the browser extension I should be able to press Ctrl + Shift + L to auto-fill login forms. I've tried this on Firefox (64.0) and Chrome (71.0.3578.98) and it doesn't do anything at all on either browser. Auto-fill from the BitWarden icon and from the context menu both work as expected.

Ctrl + Shift + Y works, and opens the app in both browsers. The shortcuts listed in chrome://extensions correctly shows Ctrl + Shift + L as the auto-fill shortcut.

Any ideas?