We might see some cases were usernames are not captured for few clients even though DHCP option 12 is enabled. This is most likely due to static IP settings on the client or may be client failing advertise it's hostname in DHCP request.
The hostname of a device is advertised in DHCP request, when it tries to get an IP address. With DHCP option 12 enabled on the Controller, the Option-12 field in the DHCP request stores the hostname which will be used to update the index "Name" in the user-table. This will help WLAN admin to identify the clients using it's hostname.
If the "Name" is not updated in the user-table, it could be either due to static IP settings on the client in question or client not advertising hostname in the DHCP request. To identify the same, we need to verify if it's a static IP on the client or collect DHCP captures from the client.
Below DHCP capture shows the hostname stored in DHCP option-12 filed, which is then used by the Controller to update hostname in the user-table.
User-table output from the Controller:
If it's found to be a static entry on the client, we could avoid such instances by enabling "Enforce DHCP" option from AAA profile. Once this is enabled, Controller ensures only the clients that gets an IP address from a DHCP server be allowed in the controller’s user-table.
If it's found the client failing to advertise it's hostname from the captures, it's a client issue and customer will have to reach respective vendor to fix it.