Just wondering if you did manage to solve this and if so how exactly. I'm looking to setup something similar, DHCP running on MX and DNS pointing to internal Windows DNS server but want to know if i will encounter this or other issues. If this will still be an issue then I will look to setup both DHCP and DNS forwarding to internal Windows servers.
I have not found a solution to this and after opening a ticket with Meraki support was told this was not a feature they supported and suggested I put in a wish. I did so, but we all know how long that can take, so we have to find another solution. I'm considering both using IP reservations and then updating my software that does reverse DNS lookups to use IP's instead of names, or moving back to Windows DHCP.
Realising this is an old thread but thought I'd share this. In a nutshell: "Clients with dynamically-set network connections (DHCP clients) will communicate with both the authoritative DNS server and the DHCP server for updating A and PTR records. The DHCP client will communicate with the authoritative DNS server directly for updating its A record, but the DHCP server updates the DNS server with the client’s PTR record on behalf of the DHCP client."