This issue has been closed as 'Won't Fix' due to an extended period of time without updates. If this issue is important to you please let us know by posting on the AnswerHub or UDN, and Epic will re-open the ticket for further review.
User reported being unable to push to devices from mac if they have their Certificates in the System Keychain rather than Local
1) Launch Keychain Access
2) Unlock System Keychain
3) Drag iOS Dev Certificates into System
4) Launch UE4Editor.app
5) Select File > Package > IOS
Head over to the existing Questions & Answers thread and let us know what's up.