With the addition of the caller ID feature available in version 58.0 of the SugarCRM mobile app, there is now an additional step required to create and sign a build for Apple using the SDK. You now must create an application ID for the Call Directory extension in addition to the main app and then create an application group to add both application IDs to.
See the App Signing for Mobile SDK article for the steps to do this. Specifically, the Creating an Application Group ID section is new, and the section below that, Creating an Application ID, must be repeated for the Call Directory extension.
And be sure to check out the caller ID functionality - it is available for both Android and iOS to help users differentiate key clients from unsolicited calls!