The one thing I think of, too, especially after Mollie Tibbett's case, is that often times, when out hiking/biking/running, you run a fitness tracker of some sort to track your mileage (I know I do). It could just be on a phone or Apple Watch or might be a FitBit. I wonder if she had one of those things running and if that might be providing clues to LE that are concerning to them.
Even if cell phone coverage is spotty (I'm not saying it is but sometimes it is in the mountains), I can't imagine not taking my cell with me on a bike ride alone just in case. But who knows how she felt about having her phone on her. We don't even know where the phone is, correct?