Quite often it's impossible to clean up sessions that contain offline clips that are unused because they are part of a clip-group that is still in the session.
Please add an option that show the parent clip-group that the selected clip belongs to.
this is partly related to this request:
Once clips go offline and live inside a clip-group it's impossible to find the offending group because when you select the offline clip in the clip-list the time-line will not jump to where the parent group lives in the session.
It's literally impossible to clean up the session once this happens. It will show a red timeline for ever.