If Layout Builder used to display paragraphs field, editing of the paragraph with Frontend Editing ("Enable Ajax content update" is turn on) results into disappearing of the field from display. The changes saved and visible after page reload, so the problem is with AJAX callback only.
1. Create content type with Paragraphs field
2. Enable Layout Builder for this content type and put Paragraph field into layout section
3. Enable and configure Frontend Editing so you can edit paragraphs, enable "Enable Ajax content update" in UI settings
3. Create content of this content type and add some paragraphs
4. Go to created page and edit one of the paragraphs using Frontend Editing, click Save
5. All paragraphs disappear, no errors in log
Update FrontendController's update content method, so it respects Layout Builder settings
Active
1.8
Code
Tested the MR, but there is something wrong with AJAX:
Follow the Steps to reproduce above, it will work and paragraphs won't disappear, then try to edit the same paragraph again and AJAX will fail, the form will open in full window and if you try to save, nothing happens.