Check:
1. Keyboard shortcut — Mac: `Cmd+K`. Windows/Linux: `Ctrl+K`. Some laptops require `Fn+Ctrl+K`.
2. Focus — are you working in a text field? `Cmd+K` sometimes doesn't work if you're typing in an input. Click outside the field first.
3. Browser conflict — Chrome and Edge also used `Cmd+K` / `Ctrl+K` for the URL bar in older versions. Update your browser.
4. Extension — a keyboard shortcut extension (Vimium, etc.) can override the combination. Test in incognito.
Clicking the search icon in the header always works as an alternative.