commissioning problem

[ReggiePye]

I just wired up a new machine and when commissioning it I found a strange problem.
I can home no problem. When I move the X axis in a positive direction it works fine but when I try to move back again in the negative direction it goes positive instead.
Same with the Y axis.
The Z axis works fine both up and down.
I loaded a file after homing and then moved in the positive direction to about the centre of the table.
I then tried framing the loaded file and it frames correctly moving in a positive direction and a negative direction.
Have I done something wrong, any other way to test my setup?

Windows version 10
Engraver brand and model DIY
Grbl version 1.1h
LaserGRBL version latest

[ReggiePye]

In desperation I just tried something.
I downloaded and installed UGS and using the same wiring, same GRBL settings it all works fine as it should.
I can't understand what is going on here.