Hi, @JohnK2021, welcome to the community, I assume you have successfully set up your "Sense" and it has paired with the app on your phone. May I draw your attention to this article How do I track breathing rate in the Fitbit app? You will see you need to wear the device 24/7 and to be sleeping at least 3 hours.
So far as your HR is concerned What factors can affect my heart-rate reading on my Fitbit device? provides guidance and advice. your HR must be turned on, you will see a flashing LED on the back of your "Sense" which must be in contact with your skin. Note also Tattoos may stop it from working.
I hope this helps be please post here again if you are still stuck.
Cheers
Gr4ndp4 | UK
AWAKE! for morning in the bowl of light has cast the stone that set the stars to flight.