Somebody in a similar thread reported that if you wanted to be on the waitlist at the gate you had to ask within a certain time window AND ALREADY BE ON THE EARLIER WAITLIST.

So a logical meaning to your case would be you are now eligible to be up'd at the gate, but they will not be scanning in advance for you.

FYI, I can say for a fact that I have been waitlisted but was able to grab Z when I called in (they had not processed me automatically). So phone calls and/or Expert Flier would be good.