I guess this is my problem too. I have a Samsung Galaxy s5. It updated to Marshmallow a few weeks ago. I use a RFLKT along with the Topeak Panobike speed and cadence sensor. The combo was working fine, with Marshmallow and the Wahoo app (the only app I could get to work with the sensor except the Topeak app which I didn't like), until last week. Now it's constantly dropping the connection with the Topeak sensor. It's strange that it was working with Marshmallow until last week, and then it worked 1 day out of 4.