ProSeries support also asked me about the two realms.  Again, I have no idea how that happened.  An when I log in to the other realm (I'm given the choice when I log in to Link), no clients at all show up.  But I agree that this probably contributes to the issue.

Thanks for trying to figure this out. I appreciate the time you've put in to this. I'm still holding out a very small glimmer of hope that someone at ProSeries will finally figure this out.