I see nobody replied ever so this may be too late but here goes. I had the same issue until I figured it out. Go in first person mode, so take direct control. Go next to the wall in the booth and the targets will pop-up. They may go down after a few seconds so you need to be quick.
Later I also managed to do this while not in direct control, you just have to be in the booth, you may have to try a few times to get in and out the booth before they pop-up but it should work.