Something told me it was an iOS limitation, to which my surprise level is exactly zero. The iPhone is my work phone where I don't really want to go down the road of installing apps for personal use on it, though I do keep the UI3 entry bookmarked in my browser. Personal and work phone are different providers, so having a means of tapping into live video quickly in an emergency is helpful in the event I'm in an area where my personal phone has no signal but the other does. I can live with no audio on that one. It just stood to burn my curiosity without knowing exactly why it wasn't working. Your insight helped though -- appreciate it.I recommend the official Blue Iris app from the app store on iOS. Many of UI3's features including H.264 and audio playback do not work on iOS because they have a terrible web browser and won't let third-party web browsers use their own rendering engines.
If you open main menu > About This UI, it should list all the unsupported features, which are quite extensive. However I just noticed the feature detection was broken on iOS and have just pushed a fix to github; it will likely be at least a few days before a Blue Iris update includes this.