rover immune to artillery fire

[bvanevery]

Why is this enemy rover immune to my artillery fire?  I hit it with 2 Impact Batteries and it didn't take a scratch.  It should be half dead or more.  It is sitting on rocky terrain with a 1-3r-1 unit that I've badly beaten up with those same artillery pieces.  Previously the 1-3r-1 was alone, then the 4-1-2 joined it.  I suspect there's some kind of bug where some units in a stack are immune to damage.  I've seen this happen in cities before, but it's usually been with armored units so the bugginess of the behavior was debateable.  No question that unarmored rovers are supposed to take artillery damage though.

This is a Yitzi patched game, if that is helpful to know.

[Geo]

That rover must have a prescient driver, knowing were every shell will impact...

[bvanevery]

Or he's piled the dead corpses of his armored comrades onto his vehicle.

[Geo]

Reaver time!  (Serenity movie)

[Mart]

Impact against 3r may be just too weak to inflict larger damage. I would suspect this reason.

[bvanevery]

That's how it works?  Calculating damage against a designated defender, rather than calculating damage individually against everybody?