Something that you may be overlooking in your claim that the Bolt's feature isn't working correctly or to your satisfaction is this: The Bolt calculates your average cadence in real time, whereas a website, such as Strava, uses data from an uploaded file and uses their own algorithm to calculate what they display on your ride page. And I really do think that Strava, and some other sites, exaggerate their data. In any case, I would tend to go with the real time data rather than calculated data.

An example: Yesterday's ride my Bolt showed an average cadence of 54 rpm. I'm not a high cadence rider so that about sounds right. I send my rides to Strava and RWGPS to share with my friends. However, I also store all my rides on my phone using Cyclemeter because the database is local to the phone, the statistics are better than any website and I don't have to have a WiFi or cellular connection to see my stats. With the ride above, the average cadence on Strava was 65, on RWGPS it was 64.8 (how they got .8 is beyond me) and on Cyclemeter it was also 54. So maybe the feature on your Bolt is working properly and it's the websites that are off.