If LE is getting Fitbit data, they almost certainly know if she was abducted and where that took place.
Fitbits work with your cell phone to transmit your location by using the cell phone's GPS signal. It updates on a frequency basis, if you have it set to be tracking your location (whether it be walking, hiking, running.) It does this no matter what, as I found out once when I went on a hike and turned my Fitbit GPS tracking on, completed the hike, and was driving home when I noticed I forgot to tell my Fitbit that I was no longer hiking. It recorded my footsteps accurately but added ten miles to how long I had "hiked", and if you look at the Fitbit dashboard, you can clearly see I was going very fast along a road. I've only made this mistake once with a few months of Fitbit usage.
If her Fitbit was forcing GPS data to be transmitted and she was abducted at home, I assume they'd put her in a car. Her speed would easily show that she was moving at the speed of a car, not the speed of a runner. Similarly if she was running and abducted then, she would suddenly be moving much faster. If her cell phone was ditched at this point, preventing the Fitbit from communicating with the servers to send GPS coordinates, then we'd know where that happened. If her Fitbit wasn't sending GPS data, I'm not sure we'd hear all this fuss about the Fitbit at all since the police could have used cell phone records to get a (less accurate) idea of where her phone last was.
This also makes sense if you look at her missing items including the iPhone jogging band and headphones. If she used the GPS feature, she'd be turning it on as she was leaving the house, or turning it off as she got home. During the run, it would be on. And of course she would have those items with her if she was going for a run.