iMovie media library no longer flags clips used in timeline??

I recently updated to 15.1.1 and iMovie 10.4.3 Somewhere along the line, iMovie has stoped putting a flag in media clips already used in the timeline. I have 10 clips that all have similar starting frames and I have no idea which ones I have dropped into the timeline. This used to be flagged in the media library so you could quickly see which clips you have used? Has this been removed, or is something not working/not turned on? I have checked settings but do not see anything for this. Any help appreciated!