Hi there! Hope you’re having a wonderful day.
I’m Yussuf and I use the Nike Run Club daily every morning. I also had this issue when I first installed it. The app doesn’t register my heart rate nor my calories so I did some digging in the app settings and found the cause of this issue. Rest assure the solution is very simple.
First I need you to check if Nike Run Club app has the required permissions:
To do that open the app and navigate to setting (click your profile anywhere and tap on Settings then Run Settings)
now navigate to Apple Watch Setup as shown in this screenshot below 👇

Then make sure everything here has the green check mark ✅ especially the health section. Check the screenshot 👇

If you’re having issues with heart rate not showing up then probably the last section will show ❕ Symbol instead of ✅
Here’s the solution:
Open Health app and tap your profile on the top right corner:


Now tap on Apps under Privacy Section:

Then find Nike Run Club app and tap on it:

Finally Turn-on everything on this page:

Hope this was helpful!
PS: you can do this for every fitness app you have to get the best results.
Cheers!