We don't have info about when and who inserted Actual Start Date on a task

[razlaz]

When a task is set to In Progress, the assigned user can manually change the Actual Start Date on the task. However, this is not logged anywhere (that I am aware of). Can I turn on logging of the "Actual Start Date" change in the System Activity section, like it is the case with Planned Completion Date? E.g. "so-and-so changed the due date to <date>" is always logged in the updates of a task.

[KellieGardner · Accepted solution]

Yes. If you are an admin and have access from setup you determine which fields are tracked. 

https://experienceleague.adobe.com/en/docs/workfront/using/administration-and-setup/set-up-wf/system...