I have the Ortur LM2 and the latest Lightburn version. I added air assist to this setup and every time I start a job and turn on the air assist compressor the software/machine locks up meaning it stops the burn and does not responds and I have to shut down LB and start it back up without the AA then the laser responds to LB.
I have the frame and laser unit grounded per Orturs instruction. Also have upgraded the controller with latest firmware.
I have the air line zip tied to the wiring harness and the compressor about 5ft away from machine and on a separate circuit than the PC or LM2.
Sounds like you’ve checked for all the right things. I suspect even with your attempts you’re still getting some sort of interference from the compressor.
The 3 things I can think of that would affect the laser in the way you describe:
drop in power - I’m trying to think of a way to even out the power. Do you have access to a UPS that you could put in front of the laser?
electrical noise from the compressor causing signaling issues - I’ve heard of filters you can put in between outlet and plug to suppress noise. It’s possible the UPS does this by default.
static discharge - this one seems the least plausible to me but probably the easiest to rule-out. Ortur doesn’t have you ground the chassis to the ground terminal of an outlet (at least with the official kit). If you haven’t already, trying grounding to an outlet. Normally you connect to the cover plate screw. Else you could use an adapter that allows you to use one of the ground terminals.
One option would be power the pump prior… let it settle THEN start the job as a test
or… have ortur draw simple squares at low power and turn pump on and off to confirm
EMF might be a problem for sure if the compressor is high power.
I would lean towards RFI since you have the items on different circuits. Compressor motor probably has brushes which will create a lot of noise. You may be able to tell by using an AM radio tuned off station and trace the noise. Test with the compressor on then off.