iPhone always shows full names of contacts
I changed settings to show only the first name of contacts. (Settings > Contacts > Short Name > First Name Only).
However in Email and Messages, the full names always appear. When "Prefer Nicknames" is activated, nicknames do appear. But generally both first and last names appear regardless.
Device is up to date (iOS 12.1.2) but this has gone on a while.
Suggestions appreciated.
iPhone SE