So it happened to me a couple of times already, last time 2min ago :). Ranged troops (artillery, ships) were commanded to attack stationary enemy unit and on attack they didn't deal damage and their attack timer was set. On recommanding attack it says sth like 5 seconds to target, yet the artillery/ships stand still. I have to move them manually forward and then command attack for it to work.
It's really annoying to see after an hour that your troops were shooting the air for all the time.
It's really annoying to see after an hour that your troops were shooting the air for all the time.