Two thoughts to share with you.
The first is to make a run to a Kleen Tank dealer close to you. They are amazing and will get that tank clean.
The second is to try Tank Blaster from Thetfold;
https://www.thetford.com/product/tan...-tank-cleaner/
Follow the instructions, however, let it sit for a full day or two. This should dissolve (resolve) the poop pyramid. I have been very pleased with this product and it works great!
Best of luck...