If watch stops tracking heart rate for some reason during training it never start tracking again to end of trainning. You have to run another trainning to watch start tracking heart rate. It's very annoying and for now this watch is useless for sport activities until update fix that issue. S3 Frontier if loses tracking heart rate after some time start again tracking but GW4 dont.
Second issue is with notifications- after update samsung calendar don't wake up display and watch don't vibrating