Welcome to the Lightburn forum! You are going to be amazed by the level of support by users here.
Read thru this thread, paying special attention to the parts about home left-front and statements about G10. Home front-left puts the machine workspace in the +X+Y quadrant. This is needed by Lightburn. I believe you can set $10=2 to get it to report work position rather than machine position.
I am guessing you have a Sainsmart 3018 machine. I too have one, Y-extended to 3040, and I restored it back to CNC use. A Sculpfun S30 Pro took its place.