Time synchronization Issue on IP phones

We are experiencing an issue with the time synchronization of IP phones in a client installation with VitalPBX R4. Although the XML file in provisioning has the client’s time zone and NTP server settings correctly, as can be seen in the screenshots and attached text file, the device’s time is one hour ahead of our local time in Bolivia (GMT-4).
The client installation has been working fine since its implementation last year in November, however, the time shifted forward on its own at the end of June. These was was reported to us in mid-July, and despite our efforts, we are unable to resolve it.
GXP Template example.txt (94.5 KB)