Garmin Forerunner 35 Bluetooth

I decided 6 months ago to ditch the HRM strap for a watch and bought the Forerunner 35. It connects no problem with my Edge 530 and the Tacx training app on Android. The only way it will connect on TDA is through ant+. I feel a BT connection on TDA is more responsive with my Neo than ant+ so would prefer to use BT for both. Why will my Forerunner not connect using BT on TDA?