Same issue here overnight last night. Some insight would be nice.
The assigned policies were renamed leaving clients assigned to policies that no longer existed. Since then, these devices were connecting to a VLAN that they should not have been on.
Our Group Policies were duplicated twice--one "from appliance" policy, one "from wireless" policy.
It looks now like we'll be spending some time fixing policy names and manually assigning devices back to the policies they were assigned a few hours ago.
We are also noticing that all of the affected clients are now assigned to the "Custom" group policy setting and not the "Normal" or "Group Policy" setting they were assigned previously...