Hi David,
There is a similar topic on this forum post:
https://community.pix4d.com/t/4568
Check the workflow suggested by Vertical Aspect it seems to work in every case.
Make sure to select the correct drone in Settings > Drone type for this app. The WiFi is not needed to connect the Inspire 1.
Make sure also to force close all other app that are using DJI’s SDK and the DJI Go app.
When you connect the phone to the controller, the controller is recognized if there is a message offering to start DJI Go. Make sure not to start DJI Go.
Hope it helps!