Gaucho SACD 5.1 mix - error on master tape?

I saw this on another board, and listened ... lo and behold, the intro to "my Rival" in the surround mix is different than the stereo versions. The MC mix does not start with the drums, just the keys.

I'm wondering if the drums were on the stereo masters only, and if not, how did they get left off? It doesn't ruin the experience for me, but my guess is it's not on the multitrack masters, much like the original masters which were used for the MoFi of the Rush "Signals" album is missing the 2nd verse from "Digital Man", but it's on another master which PGD has (but not on the "true" master).

 

Yeah, I noticed that as well. Must have lost that multitrack bit. Actually, it's just the "steel drum" type part. The basic drum track is there.

Made me do a double-take when I first heard it. Hey, at least it's on the stereo mix!