Got my 945 yesterday and set it up. Everything seemed to be working fine initially.
During the evening I went through some settings and turned on HRV Logging, Sleep/All-Day Pulse Ox, etc.
After this I noticed all heart rate data started displaying "--" with maybe one value every few minutes at best before going back to "--". Stress measurement started showing "Check watch fit" when trying to do a measurement and I was unable to get a single Pulse Ox reading during the whole evening. I went to sleep thinking it might just need some time to adjust.
I woke up with absolutely no sleep data or HR data for the night. After not getting more than a few blips of wrist heart rate data all morning regardless of restarts, different clock position on wrist, band tightness or even wrist side, I went back into the settings and tried turning off the Pulse Ox sensor. After this the heart rate reading updates reliably every few second and everything seems to work again.
I have now tried this multiple times to make sure. Turning on Pulse Ox in the Sensors menu makes all wrist heart rate measurements disappear and turning it off makes them work like normal again. No Pulse Ox readings have been captured at any point and can't be captured manually either.
Anyone have any info on this? Some known software issue, a faulty sensor, something else?
Software version 2.60 (2fa11e6). (EDIT: upgrading to 2.64 beta or downgrading to 2.50 does not help. Neither did 2.70.)
Lights on the back of the watch seem to work quite differently when Pulse Ox is on, cycling through a blink pattern if that is of any value, but I have nothing to compare to. (EDIT: took a video of it since it looks like the sensor in an endless reset loop: https://www.youtube.com/watch?v=EYEoq9d9KQ8 Local Garmin support said it does not look like what their test unit looks like)