ORIGINAL: IMAC Pres

You had stated in an early post that the aircraft will fly inverted, hands off, that more than likely is the problem, its tail heavy. Tail heavy aircraft do not break well for spins and snaps. There is a common misconception that your aircraft should be neutral for both upright and inverted flight, this is incorrect, and you should have a little push for inverted flight. For sequence flight the CG should be about 25-27% MAC, if you set CG in this range your spins and snaps will be much cleaner, knife-edge flight will require less mix and landing will be easier.
What happens in an aircraft with an aft CG, as you approach stall speed, the nose and tail both tend to fall, mush, and not easily break into a spin. If the CG is forward, the nose breaks first and autorotation follows with rudder or rudder and aileron. The same forward CG works for high speed stalls (snaps), the nose breaks clean; the aircraft auto rotates and stops better on heading.
These statements are not based on my expertise, but with conversations and assistance in setting up my own aircraft with Dave von Linsowe and George Hicks.

Hope this helps and works for you,

Tom Wheeler