I seem to have confirmed a condition of the failure to record workouts (maybe not for other issues) and thus a workaround.
Short Version (just workaround)...
Workaround Option 1: Bring your phone with you on your workout.
Workaround Option 2: Do not end your workout unless you are near your phone. If you're done, but not near your phone, pause the workout (pressing both buttons will pause) until you are near your phone, then end.
Long Version (extra info, steps with Apple Support so far)...
Like others this issue started with me after upgrading to iOS/watchOS 14/7 (or possibly that is when I started noticing). The issue did not resolve through troubleshooting steps I took, the 14.0.1/7.0.1 updates did not fix, and I didn't see progress on this thread (but over 1100 people clicking "I have this question too") so I decided to involve Apple Support.
iMessaged with Apple Support this morning. They say they're aware of the issue and working on it (there seem to be a variety of issues, so they may be convoluting some issues with others). Asked me to make sure health was turned on in iCloud (so health data is backed up to cloud), unpair watch, then reset/erase phone. Restore phone from iCloud backup, re-pair watch, and upgrade both to 14.0.1 and 7.0.1. I was frank about already being on those versions of iOS/watchOS and not wanting to do the phone reset at this time (inconvenient, maybe could do later). Person was OK with that and asked if I was available for a phone call (yes).
A "senior advisor" called me back and collected information - description of issue, watch version (series 5 GPS LTE), phone version (XS), OS versions (14.0.1, 7.0.1), troubleshooting steps I've already taken (unpair and re-pair watch from backup, also re-pair as new), and URL of this discussion thread. She put me on hold and spoke with Apple Watch Support Team.
Person from Apple Watch Support Team took over the call. Said they've resolved this issue for some people by doing the steps many of us have been trying: Restarting phone and watch, unpairing watch and re-pairing, etc. She had me send diagnostics info to support for watch (looking at the results she said "everything passed") and then for the phone ("everything passed"). Checked some other stuff (location services settings) and had me "reset fitness calibration data" in the watch app. She was certain that resetting the calibration data would fix it...and asked me if I could test (go on run) to validate. I suspect she may be confusing this issue with a different issue (I saw a longer thread about GPS data for workouts not showing up or something like that).
Another person on this thread suggested not ending workout until at their phone, so decided to incorporate that into my testing. Generally I run without the phone, ending at my house...maybe on the edge of wifi/bluetooth connectivity (probably sometimes in range of able to sync with phone, sometimes not). This may explain how the issue is somewhat intermittent for me.
So I went for an outdoor run (without phone) and broke it up into two runs. Half way through the run (away from home) I ended the workout (1.01mi). Then started another. The second one I paused when I got home (1.08mi - varied route slightly to endure different distance to make them easy to tell apart), and did not end until I was upstairs sitting next to my phone. Both runs show on the watch. Only one run (the second) shows on the phone. Activity info (move, exercise, stand, steps, mileage) are the same between watch and phone. Just the workout (ended when away from phone) is missing.




