According to the Neat (not Polycom) article, Meraki's DHCP option 42 causes NTP synchronization problems in some cases.
It may be the same problem.
NTP issue with Cisco Meraki Network - Neat Support
https://support.neat.no/article/meraki-and-ntp-issues-with-neat-firmware/
> Issue specific to Cisco Meraki networks
> Cisco Meraki networks have a known behaviour wherein, if no valid NTP server is configured by the network administrator, the Meraki Gateway populates the ‘DHCP option 42’ field with its own IP address. However, Meraki Gateway is not an NTP server and therefore it doesn’t respond to any NTP traffic.