If all stats (Stroke, Calories, Speed, Output(Watts), and Distance) are remaining at zero except Resistance, and resistance it is changing accurately in the app, then you likely have a defective speed sensor. This is not the same thing as "My resistance is correct all other stats are off or not accurate."
It is only if all stats except resistance remain at zero.
Depending on your rower the warranty procedure could vary, please contact Echelon to discuss the issue you are having.