I have a 2014 30.2 and had the same issue with the toilet as many do. I have found that keeping a half tank of water in the black tank will keep the solids from hardening, and fill the toilet bowl all the way up with water prior to flushing to help wash the solids down to deep end of tank.
I bought my unit used and found that the black tank had a hardened pile of POO under toilet exit pipe, I found this by drilling a hole in passenger side of black tank 1 3/4 inch big so that I could visually see the toilet exit. it took me 15 minutes with a high pressure hose to break apart my pile. since I have cleared the pile and using the full bowl technique I have not had any more issues with the toilet.
Brian and Lora
1 Giant, 1 Mini Schnauzer
2014 Thor A.C.E 30.2