We have a similar setup. However, we cannot pass VLAN information from the Meraki MX to the Meraki switch. DHCP Dies through the Calix GPON ONT to the Access Point Clients. DHCP is fine however from the AP's isolated NAT10.0.0.0/8
I have been searching for a solution to this for a very long time.
If the access point is connected directly to the ONT Bridged DHCP is fine. However, if it goes through a Switch I get no DHCP from the local network.