I've had connection issues with my android phone (Nexus 6P) using both bluetooth and using the bridge. The app is really unreliable about connecting to the lock. I wait and eventually I restart my phone which sometimes gets it connected. Sense is really unreliable also. I've stood outside my door staring at the app waiting for it to connect so I can manually press the unlock (or lock) button, but eventually pull out my key. Once inside the house i'll get the message that sense successfully unlocked my door.
The bridge never seems to work quite right no matter where I've put it in the house. Both the bluetooth and wifi are listed as good. A lot of times the app will show that it's connected to the lock via wifi, but when I press lock or unlock it'll tell me the bridge is down and to connect via bluetooth but the wifi/bluetooth toggle button wont work.
I've tried just disconnecting the bridge and going strictly off bluetooth and get the same connection issues. A lot of waiting for the connection to be established.
My wife has the same issues using her android phone as well.