a simple question

[FragerZ]

I was going to create another thread with this question, but it seems better to just append to this thread.

In many games, my infantry will have LOS to an enemy, but won't shoot. They'll just sit there, they'll be rested and OK, and they won't shoot at the enemy - I just finished a PBEM turn in which this happened, and 2 of my squads could see their squads at 14% exposure and firepower of about 125, and they still wouldn't fire.
I've tried making cover arcs, yet they still won't always fire at the enemy when they come into the arc, and this results in me manually needing to pick out targets for the unit in the order phase.
How can I prevent this? Or do I just have to deal with this?