I never cease to be amazed at some of the apparent anomalies in this game.
Whenever someone has melee attacked a stack of mine that has artillery units in it, my arty units can no longer conduct ranged fire as they are engaged in the melee. So today I melee attacked a fort which has an artillery unit among the defenders, and moved my own artillery units in range to bombard the fort, confident that the enemy would not be able to fire back since they would be engaged in the melee combat.
But instead, I find the artillery unit is still successfully bombarding my own artillery stack, and has already killed one unit.
Is this how the game is supposed to work? Because I've never encountered this before.