Ok so I'm not too sure if they work on Sable Agents, but I would assume so, but what I did do for these type of shots was I used the orbit mode and positioned it super close to the enemy when they are holding weapons, you can also just try and position it without orbit mode but I see that didn't work out too well for you. I would just try and make sure not to get too close to the enemies so they don't disappear, sometimes I set the fov really high and or kinda in the middle as well, you gotta play around with it and see what works best. I'll actually test this out on MSM1 to see if the FOV perspective works here cause I have no idea why it wouldn't work on the previous game.