Make sure your phone’s Bluetooth and WiFi are both turned on.
Check to be sure the mic and app are connected by looking at the small white mic icon in the upper right of the app. If there is a yellow dot on the small white mic icon, it is not connected to the app.
To connect, make sure the microphone is within a foot of your phone. Then tap the small white mic icon in the upper right of the app to bring up the “Mics” screen. Tap on the + in the upper right corner of the screen to connect.
If the issue persists, restart the app and try again.