No cardio recovery recorded on Apple Watch since 2024

It will take more than one workout, until a VO2max can be estimated by the Health App, and only those three Apple Workout types will record the needed data.

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It can take at least 24 hours of wearing your Apple Watch, followed by several Outdoor Walk, Outdoor Run, or Hiking workouts* and passive measurements with your Apple Watch before you receive an initial estimate.

If the Health app detects that your previous cardio fitness estimates could be more accurate, you'll have the option to update your data. In Cardio Fitness, tap Update under Update Your Data. After you update, the Cardio Fitness Data Updated notification shows you the results of the update and how your estimates changed.

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copied from: Track your cardio fitness levels - Apple Support

Which Apple Watch do you use?

Are you using the default Outdoor Walk, Outdoor Run or Outdoor Hiking workout to record your exercise?

In the Watch App/Privacy/Fitness Tracking, Heart Rate, etc are all enabled?

And in iPhone/Settings/Privacy & Security/Location Services/Apple Watch Workout and Motion & Fitness Tracking for Health?