I have a Stratus3 as well. Initially, in order for iFly to connect to the Stratus3 and display the informaiton, the Stratus3 needs to be in "Open ADSB" mode. I thought that iFly wsa supposed to start setting that automatically, but I don't know for sure.
The one way I know to set the Open ADSB switch to "ON" is to install the "Stratus Horizon Pro" app on an iDevice, connect to the Stratus3 and set the switch. I further think it will remain set to "ON" unless an iDevice running ForeFlight connects to your Stratus3, apparently ForeFlight automatically sets the Open ADSB switch to OFF. Also you can only run either ForeFlight, or any of the oter apps that require Open ADSB, not both at the same time.
As far as I know, the Stratus Horizon Pro app can be had for free, and is ONLY available for newer iPad, iPhone, & iPods.
https://www.appareo.com/aviation/stratus-product-line/stratus-horizon-pro-app/