Wow, no idea. If you run the mission again, does the same thing happen?
Left the mission, and was able to restart half way through. Went to Hobus 1 again, started battling the Sithesh again.... same thing happened. It disappears for a few seconds, returns but is 'stuck' in the map border. I can lock on weapons. But they just won't fire. Weird thing, the Sithesh CAN fire at me.