Series 4 LTE / watchOS 5.2.1 iPhone 8 / iOS 12.3.1
When my watch detects a workout, the heart rate display is fixed at 51 bpm. The clock records heart data, I know this because when I go to the Activity app on my iPhone, after completing the exercise, heart rate data is recorded without error. The data is stored, but for some reason it is fixed in my exercise program on my watch. Not only are Apple trainings, the HeartWatch's heart rate display is also fixed at 51. The Heart Rate app and the ECG app work without errors.
I've been trying to restart the iPhone and Apple Watch. None of the trials have been successful.