This has happened to me twice this war. I load up my raiders at the far end of a compound opposite from the defense, behind the concrete barricade with the dumpster. When the raid starts, however, they appear in the green zone at the middle of the front of the compound, totally unprotected and are immediately slaughtered. The first time I wasn't sure how it even happened, but I actually saw it the second time. Everyone was loaded up behind the barrier pre-raid, and then "boom" the raid starts and they are suddenly in the open even though I hadn't even had a chance to click on anything.