One of the "observe this" tests we have done was really simple -
we were working on getting best possible stabilized flight in a very high AOA -aprox 45 degrees to 75 degrees.
One model had a tendency to dart off quickly to one side -or the other-sorta like the wing quit on that side.
This was the first time we tried simply adding about 30% to the elevator and rudder area ( just some 3mm foam plate and CA and back in business.)
this fixed the problem -instantly.
Another new model - same thing - the fix again the same setup -except in this case the model pitched over when holding at this critical angle - adding more elevator area fixed it.
The CG can be shifted aft ,which will lessen the condition -- but the fix brings in a bad pitch couple in knife edge and when rolled to inverted - the elevator trim produces a instant -"hands off " outside looping.
None of this was likely ever seen on full scale machines but in that this is a model forum - I thought the info could help.