While in run activity there is an error of around 200 m per every kilometer and that affects the pace. I tried data recording with smart and every second but nothing makes it better. Also i tried with pretty much every gps option but it is the same
Good hint. I can also not imagine another way, how the GPS could produce an error of 20%! In my experience, 0,5% is to be expected.
To be even more specific: HRM Pro (Plus) with firmware 8.80 offers the option to be used for pace and distance measurement, indoors, but also outdoors.
Check it in the sensor settings and make sure, it is only used for pace and distance INDOOR.