One reason for "Valid RR" not staying green, or "Error Count Exceeded" is due to the user not being completely still during the reading. This may also cause the "Pulse" to go between green and red.
Another reason would be the user has a mild arrhythmia or a naturally very high HRV score. We recommend these users take their HRV readings in a seated, or in extreme cases, standing position.
Certain medications can also cause issues with the "Valid RR" during readings.
Lastly, turning your phone off, and then back on is always a safe last attempt, like restarting your computer, if the app begins to act out of sorts.