I hade the pleasure of using the company laser (5kW fibre, hell yeah!) Yesterday, and found a feature in the software I NEED in lightburn.
Micro joins. It lets you place tiny joins between the object and the waste so small objects dont flip up and jam the head. I was cutting up to 16mm steel and anything under about 200mm² got a couple of these joins.
This would be perfect for the 3mm ply I play with as I normaly have to sit with my finger over the pause button to catch flips before they get hit and ruin the job, or drop through and get scortched.
You can put down a layer of paper on top which will stop anything from burning from the back while not making it any harder to cut though. I get mine from these guys, pretty cheap and they ship well: