The flaw is that AquaMagic is the cheapest entry level bottom of the line Thetford RV toilet. By design (make that cost cutting) there is not a pipe where you'd like it to be. It just "dumps" as you've described.
We have that toilet and have actually been far more pleased with it than we ever thought we'd be. Daughter has one in a travel trailer and same experience.
This may help: Your toilet may have a VENT on the upper edge of the bowl, as you stand facing the toilet. Thetford has eliminated that vent, and recommends that we plug the vent on those AquaMagic's that still have one.
This assumes nothing else is wrong. Tank vents are properly installed, and the Dump Valves are Closed. If you're on a hookup and Valves are Open, odor from the campground sewage system will fill your holding tanks and flow into the coach when you flush.
FYI, the blade seal in our AquaMagic is original, from 2003, and it still holds water in the bowl. That, given it's a cheap design, is pretty amazing. Cheap Design? Yes, many Blades pass between two sealing surfaces. AquaMagic seals only to the Top of the Blade.