I've made this new colony just for testing this, and it confirmed my suspicions.

Here's an image of the bug happening: https://i.imgur.com/oN3xADe.jpg

Isolated everything and used just the CE package for this.

1. Harmony
   
2. Core
   
3. Royalty
   
4. Ideology
   
5. Biotech
   
6. Hugslib
   
7. Combat Extended
   
8. Combat Extended Armory
   
9. Combat Effects for Combat Extended
   
10. Combat Extended Guns
    
11. Combat Extended Armors

I think anyone can replicate this by just having two or more pawns aligned together trying to shoot something through a narrow spot. To be honest, I don't know if this is kinda of intended because this also happens whenever a target is out of the pawn's sight.

I destroyed the wall, made the pawn see the enemy and he managed to fire at it, no bugs: https://i.imgur.com/K1qGTeu.jpg

I'd like to know if someone got a work around to it. Never see ppl complaining about this specifically.