Apple Health data not syncing with Apple Fitness app

I’ve noticed that on more than one occasion the Apple Health app doesn’t reflect the activity automatically recorded in Apple Fitness app by my ZeppOS watch, and that the Health app has recorded around 4000 steps fewer than there are in Fitness.

This appears to me to be an issue with syncing between the two apps, as recording activity to Fitness has required no manual intervention into either Fitness nor the Zepp app.

I cannot see a means to force a sync, and I don’t believe that the only way to record steps into Health is by having my iPhone on me at all times!

Any help appreciated!

NP