My experience with a pin light fifth wheel (15.5% measured) and the Andersen was exactly as you described. It was a nightmare for us and we ultimately replaced it after just a couple of months. It caused my wife significant pin while towing.
I first towed that setup with my B&W Companion and didn’t experience the same jerkiness. I traded that out for the Andersen due to the weight of my trailer (21k) vs the ratings on the B&W (20k for the post version).
I went crazy and switched to the TrailerSaver TS3. It’s comically heavy but the full air ride hitch is amazing.
Longest story shortest: ditch the Andersen.
