After removing a subcollection, the subcollection's works sometimes remain listed on the parent collection's work index

1. Log in

2. Create a collection

3. Put a work or two in it

4. Create a subcollection of your collection

5. Put a work or two in it

6. Remove the subcollection from the parent collection

What happens
Sometimes, the works from the subcollection don't get reindexed and thus continue to appear on the /works page for the parent collection.

What should happen
The works should always go away.

Notes
Yes, we're sure the works weren't in both collections, and yes, we're sure it's an indexing issue – there was no collection between the work and the parent collection in the database, but the parent collection was still listed in the work's collection_id in Elasticsearch.

The collection this affected was open and unmoderated.