Test GPO read permission with PowerShell (MS16-072 – KB3159398)
Last patch-tuesday, Microsoft released Security Bulletin MS16-072. This update changes how Group Policies are downloaded to a computer which might cause GPOs to fail to apply.
A common symptom for this is that users no longer get their drives mapped by GPO.
To quote the KB-article KB3159398:
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.