Garmin Instinct Pulse Ox - not working in 11.0 software version

I have noticed that Pulse Ox not working on my Instinct Solar watch.

Its software version is 11.0 - currently this is is latest one.

I have restarted the watch, and connected to Garmin Express to check if there is any newer software version, but there was not any. 

Does anyone else has the same problem?
Do you know any solution, please?

Thanks in advance,
Csaba