Changes of last_name & first_name not shown in historical data

Hi,

I created a Custom Report for historical data to monitor changes on various attributes. When calling the API it shows all the selected attributes in "columns"

but when querying the data, I noticed that no changes for the name-attributes are being shown. (Only instances of "first_name" & "last_name" shown in the whole API Response are for the report's author and in the "columns"-section.)

Already checked the configuration in the Web-Version of the Report but can't find a reason why name changes aren't being shown. As we plan to use this API-endpoint to automate various processes (like creating/redirecting emails in case of a change of name) any help is greatly appreciated!

Best regards
Kai