I use Flitz to polish the inside of my FL rifle dies. It significantly reduces the sizing effort.
I have used Flitz to clean carbide pistol dies when I notice they have picked up brass and don't burnish the brass as well as they did. You might try polishing the inside of the die to see if will remove whatever is imbedded in the die that is scratching your cases. I'm not saying it will work, but it will not hurt anything trying it.
The dies are VERY hard. You could even use some very fine sandpaper (grit of 1000 or finer) and try polishing it out. Unless you used very high speed or polished for a very long time, you wouldn't alter the interior dimensions of the die, based on my experience.