I recently started a new game (Vanilla) and built defenses, however I discovered that in narrow tunnel raiders can stand on my sandbags to shoot (line of sandbags in a 1 wide tunnel). Is there a way to prevent that ? I though sandbags were not meant to be standded on.

EDIT : for better explanations, below a link with 2 screenshots of my design, one without ennemies I though that 1 enemy would stand on the "40 uranium" spot and others would not be able to shoot me due to sandbags (enemies come from left corridor and can access my base from right corridor). But as you can see on the 2nd image they can stand on sandbags and shoot (and if there is more enemies they go stand on the 2 others sandbags to shoot from cover... So raiders can totally stand on sand bags I guess is this new?)

https://imgur.com/a/Iq5xcEc