Average Speed and Distance Stopped Working While Elevation and Route Data Works Fine.

Ernest House wrote:

Thanks but it’s the same environment where it used to work. It’s 100% failure. I think it’s using WiFi to calculate the route. I did a test where I turned off WiFi and had my wife take it on a walk while I tracked it on Find My from home. Find My reported it stayed at home.

It sounds as if GPS is not working right. (Although you indicated that elevation and route data are working.)

If the GPS is broken, there is not much a user can do other than contact Apple for service/support:

Apple Service and Repair for Apple Watch - Apple Support (IN)

It sounds like this device is still under warranty so you should proceed with a warranty repair/replacement. My daughter's experience with an Apple iPhone is that the device under warranty was replaced with a new one instead of proceeding with a repair, note that is Apple's decision to make.

Ernest House wrote:

1. My series 8 stopped providing average speed and distance for my workouts (mostly Cycling). I thought it was just a setting reset due to WatchOS 26 upgrade but past data on my iPhone shows the last time average speed was logged was May 23rd.

I have tried:

Restarting both devices

2. Re-pairing the watch from backup

3. Reseting the watch and starting from scratch

The watch was new in October 22. Is this as long as the Watch is expected to last?

I believe that you need a good view of GPS (blockage from tall building or trees or being indoors can impede GPS coverage or make it intermittent) and also a good continuous internet connection for all of those metrics to work. Some indoor locations have poor GPS and/or poor internet and same for some outdoor locations as well.