I'm viewing assets that have the lifecycle status = Decommission. I went to look at who set that status in the audit trail. When viewing the audit trail there is no recording of the change. The field actually is blank in Audit trail.
There are several default filters on the out of the box audit trail search screen: CI = No, Asset=Yes, Managed by APM = Yes.
To see the complete, full audit trail, then select CI=All, Asset=All, and Managed by APM = All.
You can also create a different default audit history search with your own default values, by making a copy of the default audit history search and changing the values.