Mapping Dell switches running Sonic OS

This suggests that the MAC addresses might either be absent from the SNMP tables or are in a format that the Switch Port Mapper could not recognise.

Could you please run an SNMPwalk against your Sonic OS, export the complete SNMP tree to a CSV file, and send it to us?

Additionally, please provide a screenshot of a few MAC-to-port mappings from the web UI or CLI of the switch. This information will help us identify what to look for in the CSV file.