Hi,
From what I understand, your squad needs to be at least 100% infiltrated to get the squad concealment bonus.
However, I had a supply raid that went to 75% infiltration when the timer went down to 0 hours. I spent 25 Intel to boost the infiltration to 108% percent or so then launched the mission.
At the start of the mission none of my non-shinobi characters were concealed. However, the number if enemies was 14, so the enemy level did properly go from moderate to light.
Can you check the code to make sure last second Intel boosts are accounted for when decided whether or not to have the squad concealed?