Embedded entity forms lose submitted form values when other form sections are being edited

Problem/Motivation

When using a task configuration form with already existing form values, and this form contains an entity form, previously submitted form values might get lost.

Steps to reproduce

It's probably happening when the form is being submitted by an AJAX callback. The submission then likely does something wrong.

Proposed resolution

Remaining tasks

Investigate and fix.

User interface changes

API changes

Data model changes