Microsoft has dilevered another mystery update to Windows 10 systems running version 1607. The KB number is KB3199209 and as said, there is no information is available about it. The update is labelled as update for Windows 10 version 1607 in Windows update and it does not require a restart.
This looks like more of under the hood changing update, as there is no change-log available yet.
The update is always available via Windows update and also on the catalog. If you want to download this via catalog here is a link: