Garrus seems to be stuck during the mission Arrae: Ex-Cerberus Scientists. What can I do to help him? Cerberus attacked and I killed them all. Now dramatic music is playing but nothing is happening. What can I do?
Missions will "stall" like this if there is an enemy hiding somewhere, as the game is actually waiting for combat to end, not a timer.
You can usually flush out remaining enemies by running out from cover, or failing that, meticulously checking every nearby nook and cranny for hiding enemies.
Try reloading an old save point...might just be a bug
I reloaded last save game after the above bug and choose my other ally to activate the AA gun and i didnt mount the gun this time and it worked for me, maybe try this if you have this issue
The AI for the invisible phantom is a little buggy, so expect this to get stuck somewhere and be stupid hard to find. There is a quick save right before the second switch so just load the last save and when the phantom drops nuke the ever loving crap out of it before it disappears.