I've inherited a Drupal 7 site that was built in 2014. We've noticed that the body field (on any content type) has a summary textarea, but it does not save data upon submission.
Also, in comparing with other D7 sites that we have, I find it odd that on this site the Body field is assigned a 'Long text' field type whereas normally the body field uses a 'Long text and summary' field type.
Also of note, the 'Summary input' check-box on the content type setting page (/admin/structure/types/manage/page/fields/body) does not exist.
Any ideas on how to debug this issue?