Problem with heart rate sensor

First of all, I would try changing the battery in the bracelet. Also, wear the bracelet on the same arm as the watch. If it does not help, try connecting the strap simultaneously also to the phone. You can do it for example with the Strava app. If you get dropouts there too, then there is a problem with the bracelet, and you will need to contact the vendor, or Coosco's support. If there are no dropouts on the phone, there is either a problem with the watch, or some compatibility problem between the two devices. In such case I would recommend contacting the support on both sides.