only 2 leds over 6 on Epix pro (gen2)

I developed an app for Spinning. It works fine since 2023 on most every wearable garmin device. Unfortunately the Epix pro gen 2 does not work. It monitors the HR but after few minutes of activity the HR stucked around 105 bpm. Fortunately one of my friend has that device and let me try some debug. I noticed that on 8 available leds only 2 are ON. In the same time i used a forerunner 965 and fenix 5x pro and all of them works fine. So i thought is not a question of coding. But if on epix pro gen2 we start one of the pre installed garmin app for biking for example i see 8 leds on and HR work fine. So now I hAve the feelings that the app need some more code to activate leds on epix. How i can debug the HR leds on epix proi gen2 ?