Allow button in Security & Privacy System Preferences does not appear
The allow button in Security & Privacy System Preferences appear in order to gain your approval after you open Karabiner-Elements for the first time.
However, this allow button may not appear in some environments.
The exact cause of the issue has not been determined, but it may be caused by the corrupted system cache by a macOS issue.
This issue may be resolved by starting macOS in safe mode to refresh the system cache.
- Restart your Mac in safe mode by this instruction.
- Open Karabiner-Elements from Launchpad to ensure that Allow button is shown on System Preferences.
- Open System Preferences and confirm the Allow button is shown.
If the Allow button is hidden, close System Preferences and open it again.
- Click the Allow button.
- Restart your Mac and boot in normal mode.