Let's start with the basics because they are often the problem.
Do you have the ground clamp on the material?
Do you have enough air. It should be set at something like 80 or so psi and the compressor should be capable of 10 or so cfm.
In the software, what do you have set as the initial height? For metal up to 1/4 inch you may use 0.06 inches.
Does the Torch Height Controller show up as connected in the control screen. Is it turned on and properly connected to the control box?
Main arc lost usually means that one of the above is wrong.
You may also let us know how thick of metal is, the amperage and the speed of the torch.