iOS 16.1.1 on an iPhone 12 Pro Max wiped Health and Fitness data

Update: It has resolved itself. About 18 hours after I updated the OS, the phone started notifying me that various apps were sharing data with the Health app. When I opened the Health app, it showed "Downloading Health Data."

I checked the Fitness app, and all the data was visible, and full functionality appeared to be restored. I checked the Watch app, and it did not freeze when I tried to get to the General settings. I shut down all apps and rebooted the phone. After rebooting, I opened the Health app, and it gave me the expected update "Welcome, see what's new" screens. After I worked through these steps, it returned to the main screen and showed that it was still downloading data.

After about two hours, the Health app appears to have fully restored all data.

In between times, the only thing I personally did was to have the Watch update its OS. I had considered uninstalling and reinstalling the Health app, but I could not do that without unpairing the phone and watch, and I could not get to the watch settings that allow you unpair.

I have no idea why the Health app waited 18 hours or so before it started synchronizing. But everything seems to be back now.

If some Apple employee saw my post and went and fixed whatever was blocking this, I offer my heartiest thanks.

Do you mean other users like this one? Ive lost all my health data - Apple Community

The reply, "Make sure that your Health data is backing up to iCloud" is not particularly helpful.

I restored from the backup dated 11/19/2022 at 4:16 p.m. I cannot imagine how that could possibly be the wrong one.