Office 365 - Outlook Group on Mobile Device

We have a salesperson that frequently needs to communicate with the sales team of the evenings.  They want to be able to reach folks from their phone using one or more of the contact groups created in Outlook.  The contact groups (private) were created in their local Outlook from the People (contacts) view.  These groups are visible from a locally installed instance of Outlook and from OWA in the web version of Outlook.  We are trying to make these groups accessible from the person's smart phone (an iPhone, IOS 10.3.2).  We are using the native email client on the iPhone and the native Contacts.  Full email functionality is present, as we can send/receive and search contacts all day long.  As well, all of the sliders are enabled to synchronize mail, contacts, calendars, reminders, and notes.  However, the contact group we've created isn't showing up. 

Perhaps someone else has encountered this, as well.  Does anyone have thoughts or suggestions?  Thank you for your time!