Moved to NSP for better handling.
Is the time zone set for the sensor under Devices -> Sensor -> Setup -> Time Zone? And is NTP configured there or under the global Devices settings?
The time shown on the sensor CLI will always be GMT, and shouldn't affect anything with the sensor firewall for policies based on time periods. You'll want to verify that the time zone is set correctly on the manager side. Have you opened a case with the support team to investigate?