I assume both of this servos are in the same channel exit and in the same gang group for example "A".

Are you watching the elevators ,you better take the servos out infrond of you and watch the servo arms direct so there is no interfering from geometrical imperfection on the links.

There is a possibility you didnt hold the stick all the way to the end point during programming thats why you could have a "dead" travel.

Try reset the group exit and program again. Let us know what happens