The vehicle may not be in the 'Not visible' list because another user with access to the Fleet module and could have enabled this vehicle before you. If historical data visibility was enabled, the vehicle will already be included in reports and shown on the map.
✅ You can verify this by checking the 'Visible without equipment' list in the 'Visibility in reports' section.
Additionally, the vehicle might only be disabled from the subscription. For it to appear in the 'Not visible' list, the tracking device needs to be uninstalled by a Mapon representative.
Limited access rights could also prevent you from seeing vehicles that were tracked but not accessible to you earlier.