When a user uploads a primary media item, whether through the Portal, Speaker Ready Room, or cAdmin, and the auto-promotion rules auto-update the Thumbnail URL, the opposite effect occurs when deleted.
For example, when a presenter deletes a presentation from the Speaker Ready Room, the Thumbnail URL used on the cAttendee website will automatically be deleted along with the primary media item ID. No auto-delete rules need to be set up.
When the presenter uploads another primary media item, if auto-promotion Thumbnail URL rules have been set up, the Thumbnail URL will be restored to the newly uploaded primary media item. Thumbnail URL auto-promotion rules can be set up in Settings > Activities > Activity details, and Settings > Sessions > Session type details.