The smart lock doesn't seem to be working for me. I have my zenwatch connected, and a trusted location of home set, yet I always have to enter my password to open the phone.
Mine works great. You didn't say you Bluetooth device was also set as a trusted device. If not you must select it as a trusted device.
On my Note 4 I had issues with my home location as a trusted location as did many others. I went in and added several points all around my house (neighbors on both sides and across the street) as trusted locations. This was the answer for me, worked fine after that. On my Note 5 I haven't had to do that.
One thing that bugs me about Smart Lock is it deactivates after 4 hours of inactivity... I think 4 hours is a good amount of time, but they could be a little better about informing us about that requirement.
I use it with my car's bluetooth as a trusted device and it works correctly (unlocking without fingerprint) in my car, If yours is still inconsistent, you might want to try removing it as a trusted device and then re-adding it as a trusted device (if you haven't already). Good luck.
One thing that bugs me about Smart Lock is it deactivates after 4 hours of inactivity... I think 4 hours is a good amount of time, but they could be a little better about informing us about that requirement.