Sleep respiration data not present


I've bought my RF945 about 2 weeks ago.

It tracks my sleep pretty well but the only metric that is missing is the breathing rate during sleep - on Garmin Connect is says that I should wear my device during the night (which I do).

HRV monitoring is on, PulseOX is off.

Respiration data during an activity works just fine.

Anyone else has the same issue?