Hey SpecialMaf,
It appears you're having issues with your Apple Watch where it will lock unexpectedly during a workout, specifically where there are tattoos under where your Apple Watch sits. Check out the information below from this article: Get the most accurate measurements using your Apple Watch
"Permanent or temporary changes to your skin, such as some tattoos, can also impact heart rate sensor performance. The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable readings.
If you’re not able to get a consistent reading because of any of these factors, you can connect your Apple Watch wirelessly to external heart rate monitors such as Bluetooth chest straps. Learn how to pair Bluetooth accessories.
Heart rate is one of many factors that Apple Watch uses to measure your activity and exercise. Depending on your workout, it selects the most appropriate inputs for that activity. For example, when you’re running indoors, it also uses the accelerometer. Learn more about how your Apple Watch uses GPS and the heart rate sensor when you use the Workout app."
The tattoos may make it hard to get your Apple Watch to get a reading and could affect your active workouts. If possible, during workouts you may want to use a wrist that would get better readings.
Take care.
