Hi,
Does MailTips work properly in Outlook Web App? If so, the issue is more likely related to Autodiscover. Please check if the EWS URL provided by Autodiscover is correct. If not, Outlook will not be able to contact the MailTips web service.
In addition, MailTips caches data at many levels (on the server and on clients) to keep the end-user experience quick and responsive. Sometimes the only thing that's wrong is that a cache has yet to be updated. Restarting
clients (like Outlook or OWA) and sometimes services (like IIS) can assist in troubleshooting.
Since the MailTips are controlled in the server side, we can do limited things on Outlook side to troubleshoot the issue. I'd recommend you post a new question in the Exchange forum for further assistance:
https://social.technet.microsoft.com/Forums/office/en-US/home?category=exchangeserver
Regards,
Steve Fan
TechNet Community Support