not every time you fire a bow does this happen. I've speculated it has to do with firing the bow at enemies behind obstacles maybe? game basically stops. you can scroll around and read unit descriptions but no actions. then about 45 seconds later your target takes damage or he does the dodging animation combat continues as normal from that point. for me it can happen 2-3 times a fight I use alot of archers. I use a custom faction created in the faction creator with a custom leader the race is wraiths. not tested on crossbows yet