When I spend a day without my Apple Watch, the iPhone does not record how many steps I walked.
Is there a setting that I need to change to get the number of steps?
Or do I need a 3rd party app?
Check "Data Sources" for Steps in the Health app, and see if iPhone is listed as a data source. If it's not, I think there's a way to add it, but I can't remember how I did it, sorry.