Yeah, Slyp, I was pretty much leaning toward that idea too. Like you say, there's not much point debriefing them if they weren't involved in the mission - it'd just be more confusing. The Landcruiser could've been moving along to take them onboard during the exercise, which explains its' location well. 
Hail, your explanation for Ashers' fits well too - some form of high-level technical issue that immobilized her GEAR from taking part in the op this time around.