Good question. You using standard servos?
Mine used to snap fine, and would spin fine, too... for about four outings.
I was having great fun with flatspins and such, too.
All of a sudden, I lost the ability to snap/spin/flatspin, all at one time.
I've found that I can hold the rudder straight, while giving full control at the stick,
and stall the servo, so I'm guessing I just wore out the rudder servo.
I'll try a stronger servo on the rudder, when I can get one, and see how that does...
but it just struck me as odd how it was doing it fine one day, then not the next

My CG is at 5 1/4" back from the leading edge, btw... I mounted the battery above the
elevator servo, just under the wing. that put me at 5" with no tailweight, with an OS 46.
I recently added tailweight to bring the CG back further, but no change in snaps/spins.
They just disappeared completely. Snaps are now barrel rolls, and spins are spiral dives instead