If this is the issue you are running into, all you would have to do is power your iOS device off, wait a minute, power your phone back on and try again.
But let us ensure you are having the instantly failed to find hub issue—henceforth known as the insta-fail issue.
The issue is very straightforward to resolve but first let us ensure the issue you are experiencing is, indeed, the instant fail issue.
This issue only impacts iOS users (iPhone, iPad) who are using some version of iOS 13.
The issue happens when the Sengled Home app, almost instantly, fails to find the hub when you are trying to add a new hub or adding a bulb to a hub. Almost as if the app did not search for the hub.
If you are trying to add a hub, the issue happen on the leftward screen when you tap "Next" and you get the rightward screen:
If you are trying to add a bulb to an existing hub, the issue happen on the leftward screen when you tap "Next" and you get the rightward screen:
If this is the issue you are running into, all you would have to do is power your iOS device off, wait a minute, and power it back on.
Once your phone is up and running again, power the bulb off and then back on.
Then, open up the Sengled Home app and try again.
Ensure your phone has given the Sengled Home app the "Location Services" permission.
On your iOS device(s), this can be found by tapping on "Settings", then "Privacy", then "Location Services", then "Sengled Home". Make sure Sengled Home's Location Services permission is set to "While Using the App".