Hey @JaneSherman 
Circling back for Zack.
I found this forum thread where the workaround listed below worked for an athlete:
When using 3rd party-apps, you’ll likely need to use TrainerRoad on another device (such as your iPad), if you have HeartCast on your phone.
The app used wasn’t HeartCast, however, athletes have had success sending heart rate data from their apple watch to TrainerRoad using the third-party app called BlueHeart. Once you have the BlueHeart app, here’s how you can broadcast your HR from your Apple Watch into TrainerRoad:
- Open BlueHeart on your Apple Watch.
- Pick the ‘Spin’ activity type.
- In the Devices tab of TrainerRoad, select ‘BlueHeart’ or ‘’ to connect it.
- Keep in mind that you won’t be able to connect BlueHeart (or HeartCast, I assume) to TrainerRoad if you’re running TrainerRoad on your phone.
Let me know if you have any questions about this!