Contacts added from WhatsApp disappear after a few days. Very annoying as I find myself constantly adding the same contacts. Thank you for looking into this important issue soonest. Regards
Can you clarify where you are adding them (which Address book location?)? You can open the added contact in your “Contacts app”, then should see which address book (“Device” or instead maybe some DavX account that syncs with an online provider?) If an online provider, is something causing it to be removed (another device syncing, etc.)?