I have been fighting an issue with my Genmitsu LE540 for a month and a half. Every time I think I have gotten it licked, I find out it is still hiding. I had reported a wavy burning issue and it really seemed to be a hardware issue. I got it under control but in the process, I also stopped cutting at a 45° angle and started doing a 90° angle.
I noticed today, that when I picked a location within LightBurn to move the laser diagonally, it made the move and then came back a little in the negative Y direction. Almost like an upside down check mark. If I repeat this move by selecting the two locations for the move, the Y location get further off each time.
If I key in a relative move (G91) going back and forth, it seems OK. G0 X5Y5, then G0 X-5Y-5. I do that several times and it is OK.
Here is a link to a quick video I did of this: LightBurn Jog Video