Reminds me of long ago experience
About 40 yrs ago, my uncle rented a D2 size cat to build a dike for a rention pond. He drove it to get us started, then turned it over to me--the goofy 15 year old!
It was pure sand, so the little cat pushed it well, except for the operator error (mine!). I'd lower the blade and push, then it would slip, so I'd raise the blade. This led to the obvious ripple effect! My uncle sat in the shade and watch as I made progressively deeper and bigger ripples while pushing the sand. Within 30 minutes, I had mini-berms everywhere. The more I tried compensating for the ups and downs, the worse it got.
My uncle was laughing his A$$ off! Finally, out of my desperation, he came to the rescue: He started at the back, set the blade about 2 inches off the ground, and pushed all my berms level again....
It was a real head slapper for me and a great laugh for him!
Best wishes to you. (I just bought a box blade today, so hopefully, some of the experiences will be better this time.).
ron