I have no record player operational right now but what you're telling here is odd indeed. Have you tried the other versions of "Is It So Strange"? Although it's a pitty that the Jordanaires disappeared in the background. One of the important ingredients of the "Elvis Sound" is Elvis voice blending into the harmony vocals so far he becomes a part of the harmony vocals. That's one thing I like about the seventies recordings.
A whole different thing happened in the mid-sixties with the "Harum Scarum" soundtrack. You hear Elvis singing in your living room while the music is played by a combo two blocks away from where you live.