Reddit user u/pilif:

Since September of 2016 I’m running daily and tracking the runs with the Apple Watch. Sometime last year, I have told iCloud to store the health data in the cloud and now that I have updated to an XS Max, I noticed that most of my past workout data was gone.

Don’t worry though – it’s still there, the phone downloaded 2228 (in my case) files that contain the actual workout data and it’s processing them one by one.

But the kicker: This can only run while the phone is unlocked. When it’s locked, /var/mobile/Library/Health becomes inaccessible and the process stops.

This is a solid PSA. I hear complaints about lost “ring closing” data all the time, from people who switch to a new iPhone and fear they’ve lost their workout history. Read the rest for a way the more ambitious of you can track the transfer progress.