AP Invoice Line "Actions --> About" shows Last Updated by as 5

Summary

AP Invoice Line "Actions --> About" shows Last Updated by as 5

Content

Hi Experts,

Today, business user identified some weird problem. An AP invoice came via Invoice Imaging (Header matching only),  the lines are being matched manually by the AP user. 

Upon checking, today, under the AP Invoice Lines --Actions -->About shows the "Last Updated By" field as "5" instead of the name of the person.  

User is asking where this 5 came from as there is no such user called "5" exists in Production. 

I ran the Payable List diagnostic and found the same value as "5" in Last Updated by field.