One thing that did come up at some point (and I don't recall if it was addressed yet, though it may have been) - the link field doesn't like being blank once the profile gets populated. Try putting something in there (a link back to your own MD profile works, or anything else so long as it 'looks' like a valid link).
The other problem that seemed to come up for some people was more technical, and I don't understand the details on that one, but it had to do with 'version' numbers of the profile updates not matching. That would be something to chase if the link doesn't work, though someone who understands that issue would have to indicate how to do that.