I have similar problem and just posted in different thread (Wahoo Elemnt Bolt and Blue SC Speed Cadence sensor - wobbly readings).

I am using Wahoo Elemnt Bolt and Blue SC Speed & Cadence Sensor. Please let me know if anyone has come up with a solution.

Below is image from Strava on speed and estimated power for typical portion of ride prior to addition of speed and cadence sensor


Here is same chart for different ride but with the speed & cadence sensor.