When I ride indoors on my gym's spin bike, my Forerunner says "no HR" when I scroll to the HR screen. When I sync the session with Garmin Connect afterwards, it tells me a max HR in the stats, but no average.
When I scroll through the data fields for indoor cycling when I'm away from my gym's spin bike, it does display HR.
Could this be that I have inadvertently connected my device to the gym bike's computer? And if so, how to I disconnect it? I cannot see anything obvious on the wearable or the app.