When you say air dryer are you talking refrigerated air dryer? Did your compressor run much cutting that? Maybe the compressor is running more and making more water. Looks like some of it cut ok? If so was that at the start of the cut?
I have cut a lot of product and used different plasma cutters. I have been using the hypertherm xp45. I think you are going too fast. Dial it down to 40 ipm. And the power setting around 38 to 40. Air should be about 70psi. I have run tons of 3/16 at this setting. Little to no dross and what there is comes away with a cup brush and small straight across nippers, like breaking thin glass. Because the dross hasn’t bonded to the metal. 99% of the time its clean.
How big of tank do you have on compressor and what CFM is it rated for? May have been enough to do small pieces but could be running out of air on this larger piece. To kill cosumables that fast sounds like water or not enough air if had to guess.