AWS instances can be derived from billing information but have limitations associated to the tools (i.e. rightsizing) they can be used in. To identify the instances that are currently derived, you can pull in the "Derived?" column in the Asset report. This will identify whether or not the instance was derived or is associated to a fully configured account.
NOTE: The "Derived At" column may still have information populated if an instance was derived at one time and then eventually became directly configured to CloudHealth later on.