Airport Express AirPlay Issue

I am having an issue streaming through airport express (latest) from my iPhone 6S using Infuse Pro 4.1. Sometimes no audio comes through at all. I have plugged in the Airport to both a receiver that can decode Dolby and DTS using optical audio and headphones using analog and got the same result:

Dolby Source, Dolby over AirPlay On, Audio
Dolby Source, Dolby over AirPlay Off, No Audio
DTS Source, Dolby over AirPlay On, No Audio
DTS source, Dolby over AirPlay Off, No Audio