I would need some details regarding the type of equipment that the HPR260 is interfaced with. Usually when we hear of issues with misfiring or lack of arc transfer to the plate, especially when using the 30 or 50 amp consumable sets...it indicates that one of the critical interface functions known as "Pierce" is either not connected in the cnc to plasma interface or, for some reason is not working.
The pierce function is an output from the cnc to the HPR260 that holds the shield preflow on until the pierce is mostly complete....this function allows spatter from the piercing process to blow away from the area between the shield and the plate....which can cause the pilot arc to short out and extinguish.
I would verify that this function is interfaced and is working as designed, and I would work directly with Hypertherm's tech service staff to help troubleshoot this issue.
Here is the contact info for tech service.
Best regards, Jim Colt
800-643-9878 Tel - Toll Free in USA