Fantom vehicles

[BB-Rayner]

Guys,
I recently built a mission that had several vehicles driving around the airfield aprons. It seemed like a good idea but I discovered that squad members kept crashing into them.

To avoid all the cries of anguish and blue language I deleted all the vehicles and their way points and resaved the mission.

HOWEVER When we now fly the mission I, as the mission host, do not see an vehicles but other pilots still call out in panic screaming "watch out for the truck coming in from the right". One guy even blew up when he hit a fantom vehicle.

What's causing this?