OK, I'll go out on a limb here, and say this is a perfect example of why disc brakes on road bikes are problematic. What follows is opinion, but it is based on experience.

First of all, Cannondale chose to best design practices and mount the brake behind the fork. (Yes, I know they're not alone here, but this decision compounds the complications that follow). Add to that, it doesn't appear that they did anything to stiffen the curved blade fork. So when the front brake is applied hard one fork blade flexes under the stress, moving the tip with respect to it's partner on the other blade. That makes the axle work in the tips, chewing into the metal.

These are the kinds of issues that led to adoption of through axles on high performance (especially DH) mtn bikes.

IMO, there is no cure short of replacing the fork. If the brake were forward of the blade, you might have gotten some improvement by using smooth axle faces, but I don't think that's a safe option for this bike.

BTW- expect more of these kind of issues as makers start fitting disc brakes to road bikes without doing their engineering homework.