I'm trying to track my resting and activity heart rate and my device (TomTom Spark 3) is being really temperamental. Sometimes it records, sometimes it doesn't. Heart rate is enabled. When I go to my TomTom Sports app, there's no option to see heart rate and look at my stats? When I go to Trends it's not there. And on the Latest page Resting Heartrate doesn't click through to anywhere. Please can you advise? Thanks.