Problems are being reported with the MS16-072/KB 3163622 patch. Admins are saying it breaks some Group Policy settings: drives appear on domain systems that should be hidden, mapping drives don't work, and other typical GPO settings aren't getting applied.
Although initial reports of misbehaving GPOs appeared for Windows 7 client PCs, it looks like the bug applies to Windows 7 clients, Windows 8.1, and even all versions of Windows 10 clients.
The patch in question rolled out on Patch Tuesday. Very early on Thursday morning, Microsoft updated the KB 3163622 article with this explanation:
MS16-072 changes the security context with which user group policies are retrieved. This by-design behavior change protects customers' computers from a security vulnerability. Before MS16-072 is installed, user group policies were retrieved by using the user's security context. After MS16-072 is installed, user group policies are retrieved by using the machines security context. This issue is applicable for the following KB articles:
3159398 MS16-072: Description of the security update for Group Policy: June 14, 2016
3163017 Cumulative update for Windows 10: June 14, 2016
3163018 Cumulative update for Windows 10 Version 1511 and Windows Server 2016 Technical Preview 4: June 14, 2016
3163016 Cumulative Update for Windows Server 2016 Technical Preview 5: June 14 2016
All user Group Policy, including those that have been security filtered on user accounts or security groups, or both, may fail to apply on domain joined computers.
This issue may occur if the Group Policy Object is missing the Read permissions for the Authenticated Users group or if you are using security filtering and are missing Read permissions for the domain computers group.
To resolve this issue, use the Group Policy Management Console (GPMC.MSC) and follow one of the following steps:
Add the Authenticated Users group with Read Permissions on the Group Policy Object (GPO).
If you are using security filtering, add the Domain Computers group with read permission.
Apparently, admins also have the option of simply pulling the patch.
As of early Thursday morning, none of the other KB articles have been updated to reflect this acknowledged problem. They don't contain warnings about the bug or its solution.