When my stack consists of solely artillery and tanks, the artillery are placed in the front line during attack. Wha? Shouldn't ranged units be behind flanker units, as per manual (and common sense ) even if the flanker in this case has a higher ranged rating?
Tanks have a stronger ranged attack so they go behind the weaker artillery.
It's just the way the tactical screen was programmed, not a bug.They knew it would happen they just didn't care.
If you don't like it then modify the ranged attack of tanks and artillery so that artillery is greater than tanks and thus will sit behind them in the attack window... problem solved... check out creation for other changes in the works...