Why is the heart rate monitor of my Venu 2 Plus not working anymore?

Dear all,

As posted on this forum in different instances the heart rate monitor of my Garmin Venu 2 Plus watch is not working anymore. There has been no clear reason for it to all of a sudden stop working. Starting heart rate monitoring works (green light at the back of the watch) but it immediately turns back of. 

Software issues has been named but I've not come across a clear solution yet. Is there anyone who can help me out?

Amy