Newer Android devices and certain vendor implementations of Android have additional layers of security and battery management that are very aggressive. This can force applications like BlackFog to be automatically closed and also prevent them from even starting in the first place. Vendors argue that this is required to improve battery life. Unfortunately this also means you may not be secure at all times since the service is stopped.
If you are affected by this you can whitelist BlackFog and remove it from the aggressive battery optimization list. On most devices, open settings and select battery optimization. Select “BlackFog” from the list and select “Don’t optimize” and then click done.