What happened to the gamma drone? I've lost count of the number of times I've done this alert to finish this feat. It's impossible to get the gamma drone 99% of the time, so I get the alpha drone.
It is random. Look around the courthouse on far side and on rear side (the sides we don’t go to) and move around till something appears. Look on the building tops with flat surfaces. You can go in and start looking since the gravity mechanic is turned off rather than until later in the alert.
It's just random, gamma is still there, though. You don't have to do the alert to get the bot, at some point they broke the grounding effect in that alert if you spawn in at the beginning so you can just check the 3 or 4 spots the bots spawn as soon as you enter the area. You could just form a group of 4 and disband until you get the ones you need for the feat. Goes without saying but just don't use random groups from the queue to use that method.
If only it actually went without saying. I've seen a lot of people leave mid-instance in several different instances because they didn't get what they needed for some feat. The most recent was the Hall of Doom Brainiac Returns alert with the second boss not being one they needed, so they abandoned the group.