Sandbox "Defend" scenarios - Objectives remain inactive???

Just getting started on this game system!! About a week now learning the ins and outs! When I do Sandbox Defend scenarios I find that the objectives DO NOT ACTIVATE - I have commander and the required number of troops well within the RAD but the shield on the objective marker remains blank and no countdown trigger begins???? I have tried this a number of times and the result is the same... Works fine in Line-of-Sight games... I keep thinking that I must not be meeting the requirements to trigger objective but have put commander and troops right on top of it in experiments and still nothing...….. Thoughts?????

Thanks! That makes sense! Same dawned on me not long after posted the question!

Having now played through more of the official content GB scenarios I will again question why the defend objectives in sandbox games do not activate or award points for the player defender??? Many of the official scenarios like Culps Hill, Cemetary Hill, etc. do just that giving points every minute you hold on to it from the start...Also question why in sandbox the time limit for objective point awards can not be set less than 5min while in stock scenarios set as little as 1min????