Wrong pulse on Epix 2 pro

Hi,

I'm using Epix 2 pro for almost a year and very often it shows wrong pulse. For example during 1 hour cycling with a real pulse 150-160 it shows mostly 70-80. The watch was replaced with the new one, and the problem is even bigger. I hope it can be solve somehow, because pulse reading is the most important for me during trening and without that the smartwatch is useless. 

Regards, 

Wojciech