I had this problem and chose not to go through the wipe and restore as I was about to upgrade to an iPhone 12.
I just got the new phone and restored from an iCloud back-up of my old phone.
All my health data is available again on my new iPhone...
So, I would recommend you back-up your phone to iCloud, wipe it then restore from the iCloud back-up... I think all your 'lost' data will return. The wipe an restore is not as painful as you might think.
My theory is that this is not a data loss issue but a bug that just stops the data from displaying.