I finally got to the bottom of this issue. Too much enthusiasm and not enough reading on my part. Don’t change the homing position on GRBL. GRBL provides a negative coordinate system whilst Lightburn is positive. Simple solution is to apply an offset. This page explains it all very clearly.
Grbl Settings
If that is not clear for you read this as well
[Negative Coordinate Machine Setup]
I’m very please to have swapped from Uinversal Gcode Sender to Lightburn.