14.15 breathing variation doesn't work properly

Looks the same here. I also  have a pulseox turned on during sleep and no breathing variation data, exactly what you have 

I have a similar problem. For me, it works for one night then stops. Power down/up the Venu 3, then breathing variations works for one night again then stops. Yes I have PulseOx enabled during sleep.

Status update - 6/3/25: We are gathering additional information

Thanks for participating in this thread.

Can you please provide the following in your posts

1. Device SW Version
2. Garmin Connect App Version
3. Is Pulse Ox enabled for Sleep more or All-Day mode?
4. How long has Pulse Ox been enabled?
5. Please Upload the Garmin folder from your device using the steps in this article https://support.garmin.com/en-US/?faq=BAoGNOOLURAVh0AatVJiv5. If you would prefer the Garmin Express method please request a reference code
6. Upload screen shots from Garmin Connect showing sleep data where Pulse Ox was recorded and Breathing Variations are not shown and upload them using the steps in this article - https://support.garmin.com/en-US/?faq=x1XUrzdeRx84EnUCQHEKM8

Sure, today it again worked  please generate report number for Garmin Express.

photos.app.goo.gl/AubVebAakUw3kca79

My Connect version is 5.13.1.2 running on iOS 18.5. Powered down/up Venu 3 May 28 - breathing variation data ok. May 29 - no data. May 30 - no data. May 31 (today) - breathing data ok again.

Yes I would send you log files. Tell me how to extract them.

I’ve turned on the Pulse OX at night and turned my watch on and off multiple times but since the update my breathing variation feature has never worked. 

I am having the exact same problem with my Garmin Venu 3s.

Came here hoping to find the answer to the same issue. Google Pixel 7 pro running Connect 5.13, no build number.

Breathing variation has yet to show data. POx has been on for sleeping since I got the watch 4 months ago.

Happy to share log files.