Outlook 2016 and MIM 2016 client extensions.
Was recently at a client site working on group management. I discovered that the Outlook plug-in for MIM client extension is not supported on Outlook 2016.
This is not noted anywhere on the MS web site, so now you know. This is a bit disappointing, I'm hoping MS will do something about this soon. I'm going to report it on the MS FIM forum shortly.
Update: There's a hotfix see next post.