My vivoactive 3 M got replaced because of faulty pixels. However this is the second activity this week when the data of my bluetooth chest HRM just drops. HRM battery is brand new, and was working correctly with the previous vivoactive 3 M. It looks like the watch is not keeping the connection, because HR data a flat portions of just more than 1min, and the HRM has a timeout of 1 minute (before going in power save mode if there is no connection) and almost directly switches back on (because it detects connection between the chest pads). Anyone has similar issue, I'd like to now if it could be caused by the 5.4 software (my previous watch was on an older version), or if I'm unlucky and got a replacement with bad bluetooth.