Health app not updating steps in iOS 12

In iOS 12 (running on an iPhone XS Max), the Health app needs to be restarted in order to update the number of steps walked. This was not a problem before.

For example, if it says I've walked 9,000 steps today and then I go out for a walk, when open the app when I get home it will still that I've walked 9,000 steps so far today. I need to quit the app, open it again, and THEN it will say that I've walked 13,000 steps today.

This happens all the time -- the Health app always has to be restarted to show the right number. In iOS 11 it would also have the correct number every time I looked at the app. I think this is a bug that Apple needs to fix in the next update.