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