Charge 2 not showing heart rate zones

[tiswasis]

For 2 years I have tracked my HR on my fitbit charge 2. For some reason the zones arn't showing nor can I find the settings. As the main reason I use the fitbit is to monitor my heart rate due to chronic illness, this is a real problem for me. Any advice?

Moderator Edit: Clarified subject

[AlvaroFitbit]

@tiswasis Thanks for joining us! 

Let me help you with this. Is your tracker not reading your heart rate at all? Or is the data missing from the app? I suggest you clean the back of your device with cotton and rubbing alcohol and restart it. Turn the heart rate off, save and sync then turn it on save and sync again. Also check these tips to improve the heart rate reading on your device.  If it is the app could you share a screenshot? I also suggest you log out from the app, restart your phone and log back it. Make sure the tracker is syncing.

Let me know how it goes.

[tiswasis]

I will try that later thanks...
My problem is that I need the charge 5 or an app to notify me when I am going into a higher zone.
For people with M.E. the AT is 50-60% so I have to custom set those which I have done.
At 60% my AT is 90 ... above that I am in cardio or peak, a situation I need to avoid.
At 50% my AT is 75

For me it is extremely wise not to go over those readings.  I have set the watch to notify me but I have just realized my HR has been over 100 for quite a while without my noticing it (no notifications) so I have continued with the activity. 
Fitbits aren't just used for healthy people trying to get fitter but there are also a great number of people with chronic illness who are using them to monitor and pace their HR .  This doesn't seem to be being addressed ...

[Beatcounter]

I have a similar challenge, need to track actual heart rate for health versus fitness issues.  am I correct in understanding that the graph is showing an average of heartbeat rate, not the actual rates themselves? E.g., the graph does not show the true extreme highs or lows?

[tiswasis]

Sorry, I've confused matters here ...
I mistakenly responded to my own post from a year ago at least.

I now have a charge 5 but am having real difficulty setting the HR zones. I'm sorry you too have health issues.  It's really frustrating when you don't have the cognitive ability to actually follow all the online restrictions.  I am beginning to think the charge 5 is unsuitable for my needs.  It is very good in every way except for the one function I need - notification when my HR is about to go over 90 bpm so I can stay under the cardio zone.