What's the deal with Breathing Variations? Sometimes it works, sometimes it doesn't?

My FR265 recently was updated with a measurement of Breathing Variations, which shows up in my morning report. Sometimes it looks like this:

But then sometimes I get this:

It's telling me to "sleep with your device and enable Pulse Ox recording to get data." I haven't changed any settings, so why is it telling me to enable Pulse Ox recording? Do I need to turn that setting on every night?

0 ulliH 3 days ago

i have the same behaviour. therefore i deactivated "pulse ox" (on demand). with this, it doesnt annoy me any more.
the wrist based optical HR is unreliable too (for sports, for sleeping / analysis / Hrv it seems to be accurate)
this renders all the training advice/analysis/load etc. wrong.
therefore i disabled most of the fancy stuff; i only use the FR265 for sleep analysis , GPS Tracker for running, cycling.
unfortuately it is not possible to switch OHR off only for sport activities.

0 lytleric 3 days ago in reply to ulliH

Thanks, that confirms my assumption that the breathing variations feature on this watch is useless, just like the optical heart rate. I wear a chest strap whenever I use this watch for an activity. So disappointing.

0 Bitti 3 days ago in reply to lytleric

From the changelog of the latest beta:

Change log 24.04:

Fix missing breathing variations data.