Describe the bug

Synchronization using the new sync UI did not progress after a while without showing any errors. Using WP-CLI ended in out of memory conditions while indexing posts and failed afterwards in users too. So we split the command to use separate cycles for each indexable. However, this ended in users and terms to contain only 1000 documents.

I saw similar open issues but our issue is probably a little bit different. Therefore creating a new bug report to discuss further details.

Steps to Reproduce

1. Synchronize
2. Wait only progress stops
3. Displays forever the same sync message

Processed users 15400 - 15750 of 277623. Last Object ID: 797854
Processed users 15400 - 15750 of 277623. Last Object ID: 797854
Processed users 15400 - 15750 of 277623. Last Object ID: 797854
Processed users 15400 - 15750 of 277623. Last Object ID: 797854

Expected behavior

Should synchronize all indexables.

Screenshots

Environment information

• Device:
• OS:
• Browser and version:
• WordPress version:

• ElasticPress version: 4.0.1
• Elasticsearch version: 7.9.3
• Where do you host your Elasticsearch server?
• What ElasticPress features do you have currently active?
• Plugins and version:
• Theme and version:

• Site Health Info:

Additional context