We are running Microsoft Dynamics 365 version 1710 (9.1.0.6827) online for Customer Service.
We have the Customer lookup field on the case screen - out of the box. In the default view (not Unified Interface), the lookup works as designed - able to search for Accounts or Contacts.
When we switch to the Unified Interface, the Customer lookup field only shows Accounts:

The field Customer is the out of the box CUSTOMERID field.
In searching the internet, I see that I should have ALL, ACCOUNTS, and CONTACTS in the top bar to switch between. What on earth is the problem? Is it our version? I've tried other browsers with no luck. Is there a setting I am missing?