Can't confirm.
Tank/truck/car columns use the quickest way to destination.
If that's a road, they choose it, even if the target vector is 30° off the current road direction and even if the target is 30km away or so.
However, if there's something interrupting the road connection (destroyed bridge, missing road segment, whatever...), then AI can't find that "road" route anymore and will go directly to the target.
Therefore, make sure there's an uninterrupted road from your current vehicle location to the destination waypoint.
Furthermore, read, repeat, read, repeat:
You cannot spawn formations. Repeat: You cannot spawn formations.
Got it?
Listen and repeat:
An object must be moving
before you can trigger a formation command. Repeat: An object must be moving before you can trigger a formation command.
Last but not least,
make sure the formation order of all your trucks is correct.
Each truck has an index in the formation. The 1st must be index 0, followed by index 1 and so on.
If the trucks are lined up 0-2-1-3-4-5-6-7-8 they won't move. Period.
This is how you do it:
Put a first waypoint in the direction of the road, some 100 meters in front of your trucks.
Put an object link from that waypoint to all your trucks.
Trigger the waypoint from an MCU (e.g. a timer), and put another target link from the same MCU to another timer set to trigger after 1sec.
From that 2nd timer, target link to a Formation Command.
That Formation command is object linked to the Formation
Leader - and only to that. Not to the other trucks.
Finally, from the 1st Waypoint place a target link to the next waypoint and so on.
That's it.
If it doesn't work for you, please upload your mission so we can have a look at it and send a fixed version back to you for comparison.
Mike