Assuming you have a USB cable from the Mac to the laser controller, then this is likely a USB communications problem. The controller starts running the job while the rest of the data is streaming in, which means it’s trying to do two things at once, which is always a challenge.
Macs are notoriously sensitive to USB problems and you may have just rammed into a combination of updates that made it much worse.
Which pretty much rules out LB 2.0 as the cause.
The standard recommendation to use Ethernet, rather than USB, seems to cure many / most of these weird problems.