I too love my Wahoo Elemnt Bolt, and I also share your disapointment with the sensors. In the 6-8 months that I've been using the Wahoo Elemnt Bolt the heart rate sensor had to be replaced after about 4 month's and last week the cadence sensor died. Customer service has been excellent. Wahoo replaced the heart rate sensor under warranty, and they are also sending me a new cadence sensor under warranty. In both cases the battery inside the sensor died of natural causes and had to be replaced. As soon as the battery was replaced both sensors failed to return to normal function, which I found quite odd. They worked just fine until the battery died, so I have no idea why a new battery would cause any issues. And yes, I absolutely used the correct replacement battery. No "user error" on my part.
As for the Blue SC Speed and Cadence sensor specifically, it should work just fine since it's a Wahoo sensor. However, when I spoke with Wahoo tech support today about my failed cadence sensor I was told that milti-function sensors were known to be problematic. I assumed he meant third party multi-function sensors, but he didn't specify. It was a blanket statement. Now that I'm reading this thread it's possible he was including the Wahoo Blue SC Speed and Cadence sensor.
Wahoo tech support is very easy to reach and they are very helpful. Whether your sensor is under warranty or not I'd give Wahoo a call. 1 (877) 978-1112, and once in the automated menu press "3" for tech support.