How can you reset the stress monitor when it says it does not have any data on a Fenix 5X?

Is it set as the Primary Wearable Device?

Garmin Connect: Setting a Watch as Your Primary Wearable Device | Garmin Customer Support

I tried to set it but do not have the options in the link you sent.  Is there a way to update the watch or  the app?

What do you see wen you click on the icon of a watch in top right corner of Garmin Connect Web? Could you post a screenshot of it?

Here are the screenshots and I did see that the watch is listed in one screen as the primary wearable. 

Here is the screenshot from the web version. 

I want to let you know the message in the system says that there is no data.  I am not sure what or why that is happening if the primary wearable designation is showing but I definitely don’t have the same selections in the app that the system indicates.  I really appreciate your help and input!

Does the watch self show some stress data, on the Stress widget? If so, then try syncing over the USB cable to Garmin Express on a computer. If still no go, then I recommend to Remove and Add the Device From the Garmin Connect App | Garmin Customer Support, then wait a few hours, sync, and see whether it helped.