Enable the Address Relearn detection and check the log file if "address_relearn" logs are present.
If it's the case it means that the device has repeatedly learned that same MAC source address at different ports.
This process very probably indicates a loop or a shortcut (between a Rx and a Tx) on the network.

You can enable the Address Relearn detection via the web interface in the "Switching Global" menu or via the CLI in the global config mode (see below)

(SW161) >en
(SW161) #conf
(SW161) (Config)#bridge address-relearn-detect operation enable
Bridge Address Relearn Detection set to Enabled