Reindexing of multiple users after database commit is not triggered

[SarahW91]

Package version (if known): 6.0.0

Describe the bug

When creating multiple users re-indexing is not triggered for all of them after committing to the data store. Users will be properly added to the database but not the search index.

Steps to Reproduce

1. Create a loop in which multiple users are created using _datastore.create_user() with the datastore being a proxy from flask-security.
2. Call _datastore.commit() after and outside of the loop.
3. All users will be committed to the database but only the last created user will be indexed.

Expected behavior

All created users will be re-indexed.

Additional context

As far as I can see, after a user is created the database hook defined here should be triggered that re-indexes all updated users. However, at least for us this does not happen the way we expect it to.