First, I think its an old issue: viewtopic.php?f=3&t=10348&p=104852&hilit=acu+stopped+shooting#p104852
Second, mine (Sofist) ACU stopped shooting enemy ACU after I odered overcharge. It didnt overcharge and stopped attacking at all. There were multiple tagets in range. Replay attacched.
ACU was Cybran with gun + stealth upgrades.