Hi, I've tried twice to complete this lightfall mission and both times I get to this stage here (pictured) where I am supposed to have a few of those malfunctioning droids to kill that will drop the shields around the cube things, but there aren't any. Prompt says to "Kill the Vex Boss" but it cannot spawn until those things are destroyed. Any help? Praying I don't have to reinstall this game again xD