The thing Rick posted explains how the different origin settings work, but if you have a machine that hasn’t been properly zero’d there are more things at work.
LightBurn was written for dedicated laser systems, with homing and limits set properly. It will work without those things, but that’s what it assumes you have unless you tell it differently.
If your machine isn’t zero’d, then the system has no idea where you “are” when running a job - the zero point of the machine will just be wherever it was when you powered up. If that happened to be in the middle of the work area, you could have a situation like this:
The black grid is the actual work area of the laser, and the green square in the bottom corner is the origin of the machine. If the laser was sitting at the red circle when you powered it up, the machine thinks that is zero, and thinks the red square is your usable work area, which is obviously wrong.
Next, you draw this purple circle:
You jog the laser over to that corner and hit start, where you want it, and hit Start, using "current position’ as the origin mode. LightBurn asks your laser, “hey, where are you?” and the laser says, “I’m at -80, -80”. That’s out of bounds, and you get the warning.
To fix it, move the laser head to the front-left corner (or wherever you have your origin set), before you power it up, so that’s where zero goes, OR, jog the laser to that corner, and issue this command:
G92 X0 Y0
To use that, you’ll also need to have your machine sending its position in work-space coordinates. If you have an old version of GRBL (0.9 or earlier), it’s $10=2. For newer ones (1.1e or later), it’s $10=0. That means when LightBurn asks, “where are you?” it gets the answer relative to the new zero you set, not relative to where it was when you powered up. (zeroing before power up doesn’t need the above command)