Auto-saving does not work during editing.

Did you register the term from the edit page?

If you highlighted the term in the edit page to be registered to Glossary and checked the "Apply to current document" box,

machine re-translation will be done for the segments containing the term.

Re-translation will replace the already edited segments, so it could be the reason why the auto-saving did not work.

To prevent re-translation of the edited segments, do not check the "Apply to current document" box when registering terms to the Glosarry.