Most often when someone has a problem with Signal Spy, it's due to one of the following:

1. Accessibility services are not enabled. To fix: go to Android Settings > Accessibility and turn it on..

2. Android Q does not have a default dialer app. To fix: go to Android Settings-> Search for "default" -> click Phone app and make sure that it has "Phone" selected. 

3. Permissions have not been given for the app to run correctly. To fix: go to Android Settings > Apps > Signal Spy > Permissions and make sure that all the permissions are selected.