A SEPM managed Mac client may have already enabled the Pac File feature for WSS. If this Mac is upgraded or switched to cloud managed on the SES, then this configuration is not removed.
SEP 14.3 RU6 Mac clients configured to use a Pac file
When the cloud migration occurs the policy reconciliation checks policies. If there is no user policy then the admin policy is taken. The Pac file configuration will not be removed if previously configured.
Broadcom Engineering are constantly refining the smoothness of the cloud onboarding experience and this issue is not expected to apply to many customers. However, two options exist to either mitigate or resolve the situation:
1. Disable Pac File policy prior to upgrade or migration.
2. Uninstall the SEP client (which removes the Pac file policy) and reinstall SEP.