When a change is made, Blackbaud send information about the change to Audit Trail. However not all areas of changed records include the details of the person who made the change. In those cases, the 'change by' value is shown as "Not Available".
From April 2022, we have added the ability for Audit Trail to 'Infer' the 'Change By' field, based on similar activities at the same time by the same user. These 'Inferred' Changed By users are represented in Audit Trail with the user's name in italic. Due to their very nature, 'Inferred' Changed By users are suggestions, and should be considered as such.
See the user guide for more information about the specific areas that do contain changed by data.