I use Lightburn since a couple of months and thankful for this great software.
Using AWC708S controller with the Lightburn move panel, I also have the mirroring issue, but with the X axis instead of Y.
Also, I’m not very sure but I don’t think the movement speed adjusts correctly, too. Setting it down to 1mm moves like 3 at least. (holding down shift or without, when pressing the arrows on the movement panel)
I have discovered this issue while I was testing the Print & Cut functionality - there’s not a very detailed tutorial about it and I was just trying if I should use the movement control panel of the software instead of the controller, but off this topic, I couldn’t set the “Start From” to Absolute Coordinates or anything else than “Controller Setting”