I have a MR33 with code version 25.12 connected to a Zyxel managed switch and a MX64 firewall as the default gateway (DHCP server and DNS proxy as well). I have a Vizio Smart TV that I had used with the same switch and a Ubiquiti AC Pro Access point.
ChromeCast works fine with the Ubiquiti AP, but my Samsung S7 phone does not even see the TV as an Casting option when using the Meraki AP.
Both APs are configured with the same SSID and PSK, and work on the same switch port in the Zyxel switch. Only VLAN 1 is configured on the switchports, as I do not have another SSID configured on either Access Point.
The SSID isconfigured in bridge mode.
The Smart TV is connected to the switch via ethernet cable with the wireless disabled.
I have a Co-worker who is having the same ChromeCast issue with their MR33 installed at their home as well.
The company we work for has started selling the Meraki line to our small business customers, and so far no one has needed to do Chromecast at the sites we have installed them. We installed some in our homes so that we could get more experience with troubleshooting them if needed.