Found it in less than 5 minutes

Downloaded it. Wandered around the house. At first I though it wasnt working because there were some false positives which corrected themselves within seconds. Probably just calibrating the Fitbit signal. Ended up finding the Fitbit in a pile of clothes.

As an added bonus, it picked up every single Bluetooth item in the house (so I can just it for other things too!) Thank you!!

Acquired TBI about Tracker & Finder for Fitbit