Why have the upgrade option if it doesnt work
Make the Missle Lock-on Jammer work on vehicles with Imani Tech
You can also add the upgrade to the vehicles to which Rockstar added the missle lock-on jammer in the latest update
List of the vehicles: All GTA Online Vehicles That Get The Missile Lock-On Jammer In Agents of Sabotage Update - RockstarINTEL
With passive mode, no need! Check the M menu to activate this feature in any vehicle and on-foot.