The reason I can think of why you are not getting the client details is if your client tracking option is set to use MAC address instead of IP address since the client is behind a layer 3 switch. Please find the link below for the doc regarding the Meraki Client Tracking Options.
Hope this helps.
Client traking is set to MAC indeed but that honestly i do not think that would be the reason since i can see details from any other client on the Network.
Ip tracking is not available on that precise Network.
I considered to set that to Cloud tracking but since that change resets all tha Networks statistics it is not the way to go for now.
Any other ideas ??
If you are using a combined network then the IP address tracking is not available. You can uncombine the network to get that option.
It is recommended to use IP address tracking if your clients are behind a layer 3 device. If you can see details from other clients on the Network maybe its gateway IP is the MX.
The cloud track is recommended if your downstream layer 3 switch is also a Meraki. However, any change in the tracking option will reset your historical client usage statistics and there is no way to get around it for now.