My Heart Rate trend is not showing on History Heart rate either on App or Web. Shows last synced in June 2020, even though my activities show a heart rate each time

Try whether the support document Data is Missing from My Garmin Account After Syncing could help you to resolve the issue.

Having the same issue now. Were you able to resolve and if so, how?

See the previous reply, it should help you too

I did read through that document but it has not helped me. I have only ever used one email. And everything used to show but now I have no trend for HR even though for each activity it is there. 

3027427 said:

I did read through that document but it has not helped me.

Did you follow all the instructions from the document to the letter? If not, do so now, remove the device from all Garmin apps (Garmin Connect Mobile, Garmin Connect Web, and Garmin Express), sign out of all of them, then sign in back (do not sign up!), and add the device back. It will fix your issue almost certainly.

If it does not help, there are some other options listed in this post. 

Honestly don't know how to remove from Garmin Connect Web - and don't know what Garmin Express even is.

well I did remove from garmin mobile connect. And I thought I removed from garmin connect web. The instructions were not actually clear as the icon for the devices didn't bring up anything - it didn't display anything. logged out of everything. logged back in. reconnected watch to mobile app.

No joy. And now that I check garmin connect web - the watch is listed. Interesting that i wasn't before.

will try to other document you provided link to.

Did you also sign out, and sign back in with the same credentials to both GC Mobile and GC web? If not, then repeat the whole process, and do not skip the step of signing out.

yes. It's interesting that when I go to the 1 year chart now I see everything prior to March. There appears to be no data for March.