Assuming you're using a Microsoft Windows NPS (RADIUS) server, here's some more up to date Microsoft documentation for adding the IP address of the Meraki switch(es) to the server:
https://learn.microsoft.com/en-us/windows-server/networking/technologies/nps/nps-radius-clients-conf...
Without first adding those IPs to the RADIUS server, RADIUS requests may just be ignored.
Further, you can confirm the IP address that the switches are using to communicate with the RADIUS server by taking a packet capture (filtered for UDP port 1812 on whichever port is connecting to the RADIUS server) while attempting to authenticate a network client. Then look at the "NAS-IP-Address" attribute field for each switch:
It'll likely just be the management IP address, but if you're using Layer 3 routing on the switches, it might be good idea to confirm.