This sounds like a support request rather than a forum post.
I would try doing a backup and clean install of Server 7.0.12 and if that does not work roll back to the older version and await assistance from Tableau.
I already submitted support request. Just putting it out there just in case other people have expereienced the same thing.
Time to take advantage of that vSphere snapshot :-)
Was this ever addressed with your support ticket? I'm getting the same error when manually importing and syncing AD groups.