Having some issues with a CE520 and the 'switch' smartport definition.

Connecting up a unmanaged switch to a port configured with the switch smartport role and we're finding that only 1 mac address can traverse the port.

Checked the config via the web ios interface and there's no port security set on the port. Can't see why it's blocking traffic for the second mac on the unmanaged switch.

Changed the port role to 'other' which just sets up the port as an access port in an access vlan and that works around the issue. Just can't see why the switch smartport doesn't work.

Anyone had an issue with this?