Engraving screws up when using the play button in lightburn, but works fine on the controller

What OS are you using? Have you tested the USB cable, used a known good one? Have you tried a different USB port on your computer? Are you plugged directly into the controller or are you using a USB hub of some sort?

For Windows, have a look at this:

For Mac…has port lock solution. (ignore grbl part, not relevant):