Are you actually running GRBL firmware on your SKR board? Mine did the same thing at first. Lightburn recognized it as a GRBL driven machine when it was actually a Marlin driven board and it ran the laser and CNC erratically.
I found the solution on Lightburn’s forum. Simply launch Repetier Host first and hit connect. Then close out Repetier Host and launch Lightburn. After doing this the glitches went away.
This is where I found the answer (only difference is he used Pronterface instead Repetier Host but they both work):
Lastly, here’s a link to thread where Robert Bunney gave me some great help. (He’s like the laser whisperer!)