Well, it's "working" in that the adjustment changes the timing, but it's not "right"
I started playing music in the zone called "Patio". I then linked that to the zone called "Living Room", and the songs were about a second apart. I opened the timing adjustment, slid it to the left about 500ms, and it was closer, but not quite right still. It was too far to the left, so I went back to the right. I kept adjusting, little by little, while standing between the zones to hear, and finally got it perfectly synced. I walked in to see how much it needed adjusted, and it was at zero. Back to exactly where it started, with no adjustment at all! But after this process, it was now perfectly in sync between both zones.
I let it play for a few hours, and occasionally, it would be out of sync again, sometimes by quite a bit, at least a 1/2 second, but several songs later, perfectly in sync again.
Not the biggest of problems, but one that I would like to see fixed someday