Ugh this is a mess.

The output of targetAssigned is correct. Because the target is not assigned to the gunner.
The gunner gets told to shoot the target, by the commander. The gunner does not shoot the target by themselves (which happens when they are assigned to the target)
The command and vehicle target the unit, not really the gunner unit.

The weapon the unit is using, knows what its told to shoot at.
We could say "If you are told to shoot something, that should be considered target"
That would be doable, if unit has no assigned target, check if its weapon is told to shoot at something and use that instead..

But that would be better suited for getAttackTarget, instead of assignedTarget.
Mostly because the assignedTarget wiki description has more specifics that I'd rather not mess up.

getAttackTarget really is the target we last shot at. So its only set by the short being fired.
So instead of "last fired at" we turn that into "last fired at, or commanded to fire at next"

I would leave assignedTarget in the current state. so attackTarget can be used instead in this case? Is that good enough?

When the cannon is fired, assignedTarget will update

The target assigning is delayed and seems to happen just at the same time when the cannon fires, bot because the cannon fires.

It looks rather the other way around, the assigned target is set, before the main cannon fires.

Repro mission is a bit meh, only updating every 0.5s
replacing with a onEachFrame makes it much easier to see

In T154359#2602361, @dedmen wrote:

The weapon the unit is using, knows what its told to shoot at.
We could say "If you are told to shoot something, that should be considered target"
That would be doable, if unit has no assigned target, check if its weapon is told to shoot at something and use that instead..

Would it be better to add a new command then if technically the existing ones are correct? Especially in instances where it might have an assignedTarget but also another weapon target

getAttackTarget isn't well defined.
So it returning the "target the unit is told to attack" seems correct.
We're switching from "the target that was last shot at" to "the target we are going to shoot at". I think that fits.

In T154359#2602895, @dedmen wrote:

We're switching from "the target that was last shot at" to "the target we are going to shoot at". I think that fits.

Works for me