Due to a bug in the ElasticPress plugin we're not able to save EP settings. There seems to be a missing html attribute that is used to send the update request.

workaround: paste following snippet in console

document.querySelector('label[for="feature_active_documents_enabled"] input').setAttribute('data-field-name', 'active')

tasks

• If there's a new version, update to it and see if issue is solved.
• Be sure to test everything well so that updating doesn't introduce regressions.
• Add a few basic tests before updating (or create separate ticket).
• Check if this is a bug in the plugin or in our setup of it.
• Check if fix is available in recent version, or do a workaround.