"Add to Outlook contacts" and "Look up Outlook contact" are missing when we right-click on the sender's name.
This is a By Design issue
“The Look Up Outlook Contact” feature has been deprecated in Outlook 2013. And with regards to the “Add to Outlook contacts" option being missing while right clicking on a particular sender in an email…it was found that its expected behaviour if you already have an entry for that contact in the contacts folder.
Thanks & Regards