No live wrist HR after update 21.20

I'm having the same issue and "software reinstall" didn't work for me either. :( Did you have any luck with customer support? 

Two days ago, I contacted customer support, and they told me that I should sent them my watch and it will be replaced with new one. I planned to do this in the next week.

But yesterday next automatic software update was installed on my unit and it fixed my sensor's issue, BMX and WHR version are correct now and heart rate sensor shows correct data

which version of firmware? is it 21.20?

Yes, the version is still 21.20. BMX version is: 18.1.6 and WHR is: 18.01.06

please give me an update after 5-7 days of continous using your watch in 21.20 wether you encounter any error or not, i'll try to remind you next week, hope nothing bad will happen :D 

It was the same for me, it's working now. The update installed for me after I connected the watch to Garmin express. 

so how was it? does the watch running normally  24/7 for a week? curious to see if the new firmware really fix the problem

I plugged my 955 solar to a PC with Garmin Express in the past 3 days, sync-ing, disconnect, and it wasn't able to install properly; but this morning I try again, and it installed properly!
I don't know what was different.

Let's see how it hold out in the coming days.

Generally my watch is running normally during last week.

But in meantime one problem happened and it was related to another SW update: two days ago next autpmatic update was installed and again HR sensor stopped working and BMX and WHR version were 0.0.0. But then I performed software reinstall manually and after reboot it again started to work correctly.

It is working without any problem since my last post. It seems it was fixed for good for at least for me.