LE10/11 use 'arm' userspace and LE12 uses 'aarch64' userspace. The LE11 settings add-on is not showing an update because there is no 'arm' update. This also stops users from blindly updating and experiencing crashes due to arch-incompatible binary add-ons.
To do an in-place update you will need to first uninstall all binary add-ons (keeping their config). Then manually download (wget) the LE12.0.2 .tar update file to /storage/.update and reboot to update. Once the update completes you can reinstall binary addons (to use aarch64 versions).