I have a certain iOS app that's not publicly available so you won't be able to fully troubleshoot, however I can explain the behavior I'm experiencing.
When I attempt to use the app when 'Decrypt HTTPS Traffic' is disabled, the app works, but the data is encrypted and Fiddler prompts me to configure the settings.
When I enable 'Decrypt HTTPS Traffic' the app does not let me do anything and simply says 'network unavailable.'
I did install the iOS certificate. I tested on several other apps and don't appear to be experiencing the same problem. Any ideas on how I can further troubleshoot this?