cadence (accelerometer?) does work in running and walking activities

Hi all,

got a new iphone 17 pro recently and found out that cadence tracking doesn't work in all running apps that I've tried. What happens: When I start running it takes 8 seconds for cadence to show at all in these apps. When I do a speed interval it again takes 8 seconds for the cadence to display a higher number, and again 8 seconds after slowing down to display a lower number. Sometimes when I vary my pace just a bit the cadence is just stuck. I think this data mostly comes from the internal accelerometer? The GPS track, and pace curves look good. Below an example with just a short walk with an even smaller run, but basically: All my running data is useless now and I can't use cadence anymore as a metric during running. Grey: pace, orange: cadence.

I tried solving this with Apple support, but the concept of cadence is apparently difficult to understand and everyone insists that steps are tracked. Yeah, that's not what I'm interested in. Also, support insists I show this fault with an app developed by Apple. There isn't one that shows cadence if one doesn't have a watch as far as I could find out.

I wonder whether this is a hardware or a software error. Considering I see the same error across several apps, and considering I don't see complains about this online I wonder whether my new phone is a lemon. But how can I insist on an exchange if Apple doesn't even understand what my problem is and insists on an own app showing this problem?

[Edited by Moderator]