@ScholtzR about the reading from the strap, there is something wrong with the strap. Without knowing the model I would not know what to suggest, except to change batteries.
About the issue with the OHR, there is no place in Suunto that I know in which irregular heart rate is detected, there are no health features of this kind. And it is possible to turn off the OHR module during activity from the start screen, and in daily mode disabling H24 monitoring.